metacity: Fix build with musl by defining _GNU_SOURCE

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-gnome/recipes-gnome/metacity/metacity/0001-ui-Define-_GNU_SOURCE.patch

@@ -0,0 +1,27 @@
+From e7fd072f0df968f342878b77098e97ff07ed28d7 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Fri, 14 Jul 2017 10:26:31 -0700
+Subject: [PATCH] ui: Define _GNU_SOURCE
+
+it becomes portable across musl and glibc
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ src/ui/theme.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/src/ui/theme.c b/src/ui/theme.c
+index 84b57a0..c7eafc8 100644
+--- a/src/ui/theme.c
++++ b/src/ui/theme.c
+@@ -60,6 +60,7 @@
+ #include <gtk/gtk.h>
+ #include <string.h>
+ #include <stdlib.h>
++#define _GNU_SOURCE
+ #define __USE_XOPEN
+ #include <math.h>
+ 
+-- 
+2.13.3
+

meta-gnome/recipes-gnome/metacity/metacity_2.34.13.bb

@@ -13,7 +13,10 @@ REQUIRED_DISTRO_FEATURES = "x11"
 
 GNOME_COMPRESS_TYPE = "xz"
 
-SRC_URI += "file://remove-yelp-help-rules-var.patch"
+SRC_URI = "${GNOME_MIRROR}/${GNOMEBN}/${@gnome_verdir("${PV}")}/${GNOMEBN}-${PV}.tar.${GNOME_COMPRESS_TYPE};name=archive \
+           file://remove-yelp-help-rules-var.patch \
+           file://0001-ui-Define-_GNU_SOURCE.patch \
+           "
 SRC_URI[archive.md5sum] = "6d89b71672d4fa49fc87f83d610d0ef6"
 SRC_URI[archive.sha256sum] = "8cf4dbf0da0a6f36357ce7db7f829ec685908a7792453c662fb8184572b91075"