Revert "build: Tell autoconf to use a macro dir"

This reverts commit de84448e3a.

In order to make Epoxy build on Travis with the Precise package set, we
need to revert this commit, as the autotools version shipped on Ubuntu
12.04 bail out at the missing macro directory — whereas newer versions
just create it if needed.

Updating the Travis environment to Trusty allows the build to finish,
but have the knock-on effect of making more tests run — and the
EGL-without-GLX tests fail. Since there's nothing newer than Trusty on
Travis, we should back out this change until we have the ability to
build a suitable test/CI environment.

Makefile.am

@@ -20,8 +20,6 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 # IN THE SOFTWARE.
 
-ACLOCAL_AMFLAGS = -I m4
-
 SUBDIRS = include/epoxy src
 
 SUBDIRS += test

configure.ac

@@ -27,7 +27,6 @@ AC_INIT([libepoxy],
         [libepoxy])
 AC_CONFIG_SRCDIR([Makefile.am])
 AC_CONFIG_HEADERS([config.h])
-AC_CONFIG_MACRO_DIR([m4])
 
 # Initialize Automake
 AM_INIT_AUTOMAKE([foreign dist-bzip2 subdir-objects])