Remove obsolete AM_PROG_CC_STDC use as there's already modern equivalent,
AC_PROG_CC, present.

Upstream-Status: Submitted

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>
diff -Nurd pkg-config-0.28/glib/configure.ac pkg-config-0.28/glib/configure.ac
--- pkg-config-0.28/glib/configure.ac	2012-10-13 17:35:36.000000000 +0300
+++ pkg-config-0.28/glib/configure.ac	2013-05-24 23:48:34.093415116 +0300
@@ -288,7 +288,6 @@
 AM_CONDITIONAL(HAVE_CXX, [test "$CXX" != ""])
 AC_LANG_RESTORE

-AM_PROG_CC_STDC
 AM_PROG_CC_C_O
 AC_PROG_INSTALL