mate-session-manager: remove obsolete patch.

srcpkgs/mate-session-manager/patches/setlocale-needs-locale.h.patch

@@ -1,10 +0,0 @@
---- tools/mate-session-inhibit.c.orig	2015-05-21 21:08:13.349790585 +0200
-+++ tools/mate-session-inhibit.c	2015-05-21 21:08:22.765889625 +0200
-@@ -24,6 +24,7 @@
- #include <unistd.h>
- #include <stdlib.h>
- #include <string.h>
-+#include <locale.h>
- 
- #include <glib.h>
- #include <glib/gi18n.h>