[metacity] build: add AC_CONFIG_MACRO_DIR

[Alberts Muktupāvels <muktupavels src gnome org>]

commit ebfca330b5cbf0851bb13631339a7d88ddfe5bdb
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 20 01:24:19 2015 +0300

    build: add AC_CONFIG_MACRO_DIR

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index aec1ffb..8b2aa96 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,7 @@ dnl **************************************************************************
 AC_INIT([metacity], [m_version], [m_bugzilla_url])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_SRCDIR([src/core/display.c])
+AC_CONFIG_MACRO_DIR([m4])
 
 dnl **************************************************************************
 dnl Set release policy