m4: Add ibuslocale.m4 to Makefile.am

m4/Makefile.am

@@ -3,7 +3,7 @@
 # ibus - The Input Bus
 #
 # Copyright (c) 2007-2010 Peng Huang <shawn.p.huang@gmail.com>
-# Copyright (c) 2007-2010 Red Hat, Inc.
+# Copyright (c) 2007-2018 Red Hat, Inc.
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -22,6 +22,7 @@
 
 EXTRA_DIST = \
     as-version.m4 \
+    ibuslocale.m4 \
     vapigen.m4 \
     $(NULL)