autotools: emit error message when autoconf-archive is missing

Forbid the AX_COMPARE_VERSION macro from being found in the output
configure script. If autoconf-archive is not installed when autoreconf
is run, the following error message is emitted:

configure.ac:231: error: possibly undefined macro: AX_COMPARE_VERSION
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1

Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>
Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index e59f82e9..9db39232 100644
--- a/configure.ac
+++ b/configure.ac
@@ -228,6 +228,7 @@ PKG_CHECK_VAR(bashcompdir, [bash-completion], [completionsdir], ,
 PKG_CHECK_MODULES(LIBARCHIVE, [libarchive >= 3.0.0], ,
 	AC_MSG_ERROR([*** libarchive >= 3.0.0 is needed to compile pacman!]))
 
+m4_pattern_forbid([^AX_COMPARE_VERSION$])
 # Check file for seccomp
 if test "x$with_file_seccomp" = "xauto"; then
 	file_version="$(file --version| sed -n 's/^file-\(.*\)/\1/p')"