configure: remove po/Makefile.in from AC_CONFIG_FILES

Since we are gettextizing the package, gettextize updates configure.ac
to add po/Makefile.in to AC_CONFIG_FILES>

Unfortunately, it's already present, and gettextize does not detect it,
and insists on adding its own. Later on, autoreconf barfs on the double
occurences.

As suggested by Arnout, just patch configure.ac to remove the
po/Makefile.in occurence, so gettextize can safely add its own

Reported-by: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Alvaro Gamez <alvaro.gamez@hazent.com>

diff -durN libconfuse-V2_7.orig/configure.ac libconfuse-V2_7/configure.ac
--- libconfuse-V2_7.orig/configure.ac	2010-02-20 10:14:10.000000000 +0100
+++ libconfuse-V2_7/configure.ac	2014-07-17 00:19:18.816785340 +0200
@@ -49,7 +49,6 @@
 AC_CONFIG_FILES([Makefile \
 		 src/Makefile \
 		 examples/Makefile \
-                 po/Makefile.in \
 		 m4/Makefile \
 		 tests/Makefile \
 		 doc/Makefile \