configure: Don't enable valgrind unless specifically asked for

Running "make check" is quite slow if valgrind is enabled, and most of the time
failures is the result of a leak in the GL driver. Since when building packages
testing is enabled, this will make the package build fail when valgrind is
installed. So instead of automagically enabling valgrind when it is installed,
make it a configure option that also may fail if valgrind is not installed, but
requested.

v2: Use some lowercase variable to report enabled valgrind (Gurchetan)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>

configure.ac

@@ -94,6 +94,10 @@ AC_ARG_ENABLE(tests,
 	      [build_tests="$enableval"],
 	      [build_tests="auto"])
 
+AC_ARG_ENABLE(valgrind,
+	      AS_HELP_STRING([--enable-valgrind], [Run the test suite also in valgind]),
+	      [test_valgrind="$enableval"], [test_valgrind="no"])
+
 AC_ARG_ENABLE([egl], AS_HELP_STRING([--disable-egl], [Disable EGL]))
 AC_ARG_ENABLE([glx], AS_HELP_STRING([--disable-glx], [Disable GLX]))
 
@@ -102,12 +106,22 @@ PKG_CHECK_MODULES(CHECK, [check >= 0.9.4], [HAVE_CHECK="yes"], [HAVE_CHECK="no"]
 if test "x$build_tests" = "xauto" && test "x$os_win32" = "xno"; then
 	build_tests="$HAVE_CHECK"
 fi
+
 if test "x$build_tests" = "xyes"; then
 	if test "x$HAVE_CHECK" = "xno"; then
 		AC_MSG_ERROR([Cannot build tests, check is missing])
 	fi
 
-	AC_PATH_PROG(VALGRIND, [valgrind])
+	if test "x$test_valgrind" = "xyes"; then
+		AC_PATH_PROG(VALGRIND, [valgrind])
+                if test "x$VALGRIND" = "x"; then
+                        enable_valgrind="no"
+                        AC_MSG_ERROR([Cannot run test with valgrind])
+                else
+                        enable_valgrind="yes"
+                fi
+
+	fi
 fi
 
 AC_ARG_ENABLE(fuzzer,
@@ -198,6 +212,7 @@ AC_MSG_NOTICE([
       gbm_allocation:           $enable_gbm_allocation
       debug:                    $enable_debug
       tests:                    $build_tests
+      valgrind:                 $enable_valgrind
       fuzzer:                   $enable_fuzzer
 
 ])