[libwnck] Fix the build with automake 1.13

[Marco Trevisan <marcotrevi src gnome org>]

commit c5f08dc107b608c50e383f257a3cfbc914bcb5ea
Author: Nuno Araujo <nuno araujo russo79 com>
Date:   Sat Jan 19 08:16:06 2013 +0100

    Fix the build with automake 1.13
    
    In Automake 1.13, the long-deprecated macro AM_CONFIG_HEADER (deprecated
    since 2002) has been removed in favour of AC_CONFIG_HEADERS.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=692115

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ca852dc..514eb11 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@ m4_define([wnck_version],
 AC_INIT([libwnck], [wnck_version],
         [http://bugzilla.gnome.org/enter_bug.cgi?product=libwnck])
 
-AM_CONFIG_HEADER(config.h)
+AC_CONFIG_HEADERS(config.h)
 
 AM_INIT_AUTOMAKE([1.11 no-dist-gzip dist-xz tar-ustar])
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])