gnome-session: add portability patch from OpenBSD to fix musl.

srcpkgs/gnome-session/patches/patch-gnome-session_main_c

@@ -0,0 +1,15 @@
+$OpenBSD: patch-gnome-session_main_c,v 1.13 2015/04/03 12:43:19 ajacoutot Exp $
+
+XXX no rpmatch(3) on OpenBSD
+
+--- gnome-session/main.c.orig	Fri Apr  3 14:18:31 2015
++++ gnome-session/main.c	Fri Apr  3 14:19:42 2015
+@@ -260,7 +260,7 @@ main (int argc, char **argv)
+ 
+         debug_string = g_getenv ("GNOME_SESSION_DEBUG");
+         if (debug_string != NULL) {
+-                debug = rpmatch (debug_string) == TRUE || atoi (debug_string) == 1;
++                debug = atoi (debug_string) == 1;
+         }
+ 
+         error = NULL;

srcpkgs/gnome-session/template

@@ -1,7 +1,7 @@
 # Template file for 'gnome-session'
 pkgname=gnome-session
 version=3.16.0
-revision=1
+revision=2
 build_options="systemd"
 build_style=gnu-configure
 configure_args="--disable-schemas-compile $(vopt_enable systemd)"