diff --git a/build-aux/ax_code_coverage.m4 b/build-aux/ax_code_coverage.m4
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+# ===========================================================================
+#     http://www.gnu.org/software/autoconf-archive/ax_code_coverage.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CODE_COVERAGE()
+#
+# DESCRIPTION
+#
+#   Defines CODE_COVERAGE_CFLAGS and CODE_COVERAGE_LDFLAGS which should be
+#   included in the CFLAGS and LIBS/LDFLAGS variables of every build target
+#   (program or library) which should be built with code coverage support.
+#   Also defines CODE_COVERAGE_RULES which should be substituted in your
+#   Makefile; and $enable_code_coverage which can be used in subsequent
+#   configure output. CODE_COVERAGE_ENABLED is defined and substituted, and
+#   corresponds to the value of the --enable-code-coverage option, which
+#   defaults to being disabled.
+#
+#   Test also for gcov program and create GCOV variable that could be
+#   substituted.
+#
+#   Note that all optimisation flags in CFLAGS must be disabled when code
+#   coverage is enabled.
+#
+#   Usage example:
+#
+#   configure.ac:
+#
+#     AX_CODE_COVERAGE
+#
+#   Makefile.am:
+#
+#     @CODE_COVERAGE_RULES@
+#     my_program_LIBS = ... $(CODE_COVERAGE_LDFLAGS) ...
+#     my_program_CFLAGS = ... $(CODE_COVERAGE_CFLAGS) ...
+#
+#   This results in a "check-code-coverage" rule being added to any
+#   Makefile.am which includes "@CODE_COVERAGE_RULES@" (assuming the module
+#   has been configured with --enable-code-coverage). Running `make
+#   check-code-coverage` in that directory will run the module's test suite
+#   (`make check`) and build a code coverage report detailing the code which
+#   was touched, then print the URI for the report.
+#
+#   This code was derived from Makefile.decl in GLib, originally licenced
+#   under LGPLv2.1+.
+#
+# LICENSE
+#
+#   Copyright (c) 2012 Philip Withnall
+#   Copyright (c) 2012 Xan Lopez
+#   Copyright (c) 2012 Christian Persch
+#   Copyright (c) 2012 Paolo Borelli
+#   Copyright (c) 2012 Dan Winship
+#   Copyright (c) 2015 Bastien ROUCARIES
+#
+#   This library is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU Lesser General Public License as published by
+#   the Free Software Foundation; either version 2.1 of the License, or (at
+#   your option) any later version.
+#
+#   This library is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+#   General Public License for more details.
+#
+#   You should have received a copy of the GNU Lesser General Public License
+#   along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+#serial 5
+
+AC_DEFUN([AX_CODE_COVERAGE],[
+	dnl Check for --enable-code-coverage
+	AC_REQUIRE([AC_PROG_SED])
+
+	# allow to override gcov location
+	AC_ARG_WITH([gcov],
+	  [AS_HELP_STRING([--with-gcov[=GCOV]], [use given GCOV for coverage (GCOV=gcov).])],
+	  [_AX_CODE_COVERAGE_GCOV_PROG_WITH=$with_gcov],
+	  [_AX_CODE_COVERAGE_GCOV_PROG_WITH=gcov])
+
+	AC_MSG_CHECKING([whether to build with code coverage support])
+	AC_ARG_ENABLE([code-coverage],
+	  AS_HELP_STRING([--enable-code-coverage],
+	  [Whether to enable code coverage support]),,
+	  enable_code_coverage=no)
+
+	AM_CONDITIONAL([CODE_COVERAGE_ENABLED], [test x$enable_code_coverage = xyes])
+	AC_SUBST([CODE_COVERAGE_ENABLED], [$enable_code_coverage])
+	AC_MSG_RESULT($enable_code_coverage)
+
+	AS_IF([ test "$enable_code_coverage" = "yes" ], [
+		# check for gcov
+		AC_CHECK_TOOL([GCOV],
+		  [$_AX_CODE_COVERAGE_GCOV_PROG_WITH],
+		  [:])
+		AS_IF([test "X$GCOV" = "X:"],
+		  [AC_MSG_ERROR([gcov is needed to do coverage])])
+		AC_SUBST([GCOV])
+
+		dnl Check if gcc is being used
+		AS_IF([ test "$GCC" = "no" ], [
+			AC_MSG_ERROR([not compiling with gcc, which is required for gcov code coverage])
+		])
+
+		# List of supported lcov versions.
+		lcov_version_list="1.6 1.7 1.8 1.9 1.10 1.11"
+
+		AC_CHECK_PROG([LCOV], [lcov], [lcov])
+		AC_CHECK_PROG([GENHTML], [genhtml], [genhtml])
+
+		AS_IF([ test "$LCOV" ], [
+			AC_CACHE_CHECK([for lcov version], ax_cv_lcov_version, [
+				ax_cv_lcov_version=invalid
+				lcov_version=`$LCOV -v 2>/dev/null | $SED -e 's/^.* //'`
+				for lcov_check_version in $lcov_version_list; do
+					if test "$lcov_version" = "$lcov_check_version"; then
+						ax_cv_lcov_version="$lcov_check_version (ok)"
+					fi
+				done
+			])
+		], [
+			lcov_msg="To enable code coverage reporting you must have one of the following lcov versions installed: $lcov_version_list"
+			AC_MSG_ERROR([$lcov_msg])
+		])
+
+		case $ax_cv_lcov_version in
+			""|invalid[)]
+				lcov_msg="You must have one of the following versions of lcov: $lcov_version_list (found: $lcov_version)."
+				AC_MSG_ERROR([$lcov_msg])
+				LCOV="exit 0;"
+			;;
+		esac
+
+		AS_IF([ test -z "$GENHTML" ], [
+			AC_MSG_ERROR([Could not find genhtml from the lcov package])
+		])
+
+		dnl Build the code coverage flags
+		CODE_COVERAGE_CFLAGS="-O0 -g -fprofile-arcs -ftest-coverage"
+		CODE_COVERAGE_LDFLAGS="-lgcov"
+
+		AC_SUBST([CODE_COVERAGE_CFLAGS])
+		AC_SUBST([CODE_COVERAGE_LDFLAGS])
+	])
+
+CODE_COVERAGE_RULES='
+# Code coverage
+#
+# Optional:
+#  - CODE_COVERAGE_DIRECTORY: Top-level directory for code coverage reporting.
+#    (Default: $(top_builddir))
+#  - CODE_COVERAGE_OUTPUT_FILE: Filename and path for the .info file generated
+#    by lcov for code coverage. (Default:
+#    $(PACKAGE_NAME)-$(PACKAGE_VERSION)-coverage.info)
+#  - CODE_COVERAGE_OUTPUT_DIRECTORY: Directory for generated code coverage
+#    reports to be created. (Default:
+#    $(PACKAGE_NAME)-$(PACKAGE_VERSION)-coverage)
+#  - CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH: --gcov-tool pathtogcov
+#  - CODE_COVERAGE_LCOV_OPTIONS_DEFAULT: Extra options to pass to the lcov instance.
+#    (Default: $CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH)
+#  - CODE_COVERAGE_LCOV_OPTIONS: Extra options to pass to the lcov instance.
+#    (Default: $CODE_COVERAGE_LCOV_OPTIONS_DEFAULT)
+#  - CODE_COVERAGE_GENHTML_OPTIONS: Extra options to pass to the genhtml
+#    instance. (Default: empty)
+#  - CODE_COVERAGE_IGNORE_PATTERN: Extra glob pattern of files to ignore
+#
+# The generated report will be titled using the $(PACKAGE_NAME) and
+# $(PACKAGE_VERSION). In order to add the current git hash to the title,
+# use the git-version-gen script, available online.
+
+# Optional variables
+CODE_COVERAGE_DIRECTORY ?= $(top_builddir)
+CODE_COVERAGE_OUTPUT_FILE ?= $(PACKAGE_NAME)-$(PACKAGE_VERSION)-coverage.info
+CODE_COVERAGE_OUTPUT_DIRECTORY ?= $(PACKAGE_NAME)-$(PACKAGE_VERSION)-coverage
+CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH ?= --gcov-tool "$(GCOV)"
+CODE_COVERAGE_LCOV_OPTIONS_DEFAULT ?= $(CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH)
+CODE_COVERAGE_LCOV_OPTIONS ?= $(CODE_COVERAGE_LCOV_OPTIONS_DEFAULT)
+CODE_COVERAGE_GENHTML_OPTIONS ?=
+CODE_COVERAGE_IGNORE_PATTERN ?=
+
+code_coverage_quiet = $(code_coverage_quiet_$(V))
+code_coverage_quiet_ = $(code_coverage_quiet_$(AM_DEFAULT_VERBOSITY))
+code_coverage_quiet_0 = --quiet
+
+# Use recursive makes in order to ignore errors during check
+check-code-coverage:
+ifeq ($(CODE_COVERAGE_ENABLED),yes)
+	-$(MAKE) $(AM_MAKEFLAGS) -k check
+	$(MAKE) $(AM_MAKEFLAGS) code-coverage-capture
+else
+	@echo "Need to reconfigure with --enable-code-coverage"
+endif
+
+# Capture code coverage data
+code-coverage-capture: code-coverage-capture-hook
+ifeq ($(CODE_COVERAGE_ENABLED),yes)
+	$(LCOV) $(code_coverage_quiet) --directory $(CODE_COVERAGE_DIRECTORY) --capture --output-file "$(CODE_COVERAGE_OUTPUT_FILE).tmp" --test-name "$(PACKAGE_NAME)-$(PACKAGE_VERSION)" --no-checksum --compat-libtool $(CODE_COVERAGE_LCOV_OPTIONS)
+	$(LCOV) $(code_coverage_quiet) --directory $(CODE_COVERAGE_DIRECTORY) --remove "$(CODE_COVERAGE_OUTPUT_FILE).tmp" "/tmp/*" $(CODE_COVERAGE_IGNORE_PATTERN) --output-file "$(CODE_COVERAGE_OUTPUT_FILE)"
+	-@rm -f $(CODE_COVERAGE_OUTPUT_FILE).tmp
+	LANG=C $(GENHTML) $(code_coverage_quiet) --prefix $(CODE_COVERAGE_DIRECTORY) --output-directory "$(CODE_COVERAGE_OUTPUT_DIRECTORY)" --title "$(PACKAGE_NAME)-$(PACKAGE_VERSION) Code Coverage" --legend --show-details "$(CODE_COVERAGE_OUTPUT_FILE)" $(CODE_COVERAGE_GENHTML_OPTIONS)
+	@echo "file://$(abs_builddir)/$(CODE_COVERAGE_OUTPUT_DIRECTORY)/index.html"
+else
+	@echo "Need to reconfigure with --enable-code-coverage"
+endif
+
+# Hook rule executed before code-coverage-capture, overridable by the user
+code-coverage-capture-hook:
+
+ifeq ($(CODE_COVERAGE_ENABLED),yes)
+clean: code-coverage-clean
+code-coverage-clean:
+	-$(LCOV) --directory $(top_builddir) -z
+	-rm -rf $(CODE_COVERAGE_OUTPUT_FILE) $(CODE_COVERAGE_OUTPUT_FILE).tmp $(CODE_COVERAGE_OUTPUT_DIRECTORY)
+	-find . -name "*.gcda" -o -name "*.gcov" -delete
+endif
+
+GITIGNOREFILES ?=
+GITIGNOREFILES += $(CODE_COVERAGE_OUTPUT_FILE) $(CODE_COVERAGE_OUTPUT_DIRECTORY)
+
+DISTCHECK_CONFIGURE_FLAGS ?=
+DISTCHECK_CONFIGURE_FLAGS += --disable-code-coverage
+
+.PHONY: check-code-coverage code-coverage-capture code-coverage-capture-hook code-coverage-clean
+'
+
+	AC_SUBST([CODE_COVERAGE_RULES])
+	m4_ifdef([_AM_SUBST_NOTMAKE], [_AM_SUBST_NOTMAKE([CODE_COVERAGE_RULES])])
+])