[libchamplainmm] Discover path of convert_pango.m4

[Juan R. Garcia Blanco <juanrgar src gnome org>]

commit c9f6d4a76917daba6c1ea0ceba40ee25e5220662
Author: Juan R. García Blanco <juanrgar gmail com>
Date:   Sun Feb 23 13:02:24 2014 +0100

    Discover path of convert_pango.m4
    
        * configure.ac: use pkg-config to discover
            path of installed convert_pango.m4

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f3b7f97..2e45bfd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -44,6 +44,7 @@ PKG_CHECK_MODULES([LIBCHAMPLAINMM], [$LIBCHAMPLAINMM_MODULES])
 
 MM_PKG_CONFIG_SUBST([GTHREAD_CFLAGS], [--cflags-only-other gthread-2.0])
 MM_PKG_CONFIG_SUBST([GMMPROC_DIR], [--variable=gmmprocdir glibmm-2.4])
+MM_PKG_CONFIG_SUBST([GMMPROC_EXTRA_M4_DIR], [--variable=gmmprocm4dir pangomm-1.4])
 
 MM_ARG_ENABLE_DOCUMENTATION
 MM_ARG_WITH_TAGFILE_DOC([libstdc++.tag], [mm-common-libstdc++])