Define _GNU_SOURCE on non-Linux

To fix "assignment makes pointer from integer without a cast" found by
build-log scanning on kFreeBSD.

debian/patches/073-Use-AC_USE_SYSTEM_EXTENSIONS-to-get-_GNU_SOURCE-_XOP.patch

@@ -0,0 +1,112 @@
+From f9c44b6ae73233adb2420cad2d8270781d1abd36 Mon Sep 17 00:00:00 2001
+From: Simon McVittie <smcv@debian.org>
+Date: Sun, 17 Aug 2014 15:00:54 +0100
+Subject: [PATCH] Use AC_USE_SYSTEM_EXTENSIONS to get _GNU_SOURCE,
+ _XOPEN_SOURCE etc.
+
+Similar to Bug #684123 in GLib.
+
+Bug: https://bugzilla.gnome.org/show_bug.cgi?id=734947
+---
+ configure.ac                                     | 2 ++
+ gdk/wayland/gdkdevice-wayland.c                  | 1 -
+ gtk/fnmatch.c                                    | 7 -------
+ gtk/gtkscalebutton.c                             | 3 ---
+ gtk/gtksearchenginesimple.c                      | 8 --------
+ modules/printbackends/cups/gtkprintbackendcups.c | 4 ----
+ 6 files changed, 2 insertions(+), 23 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 4406403..a814abe 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -227,6 +227,8 @@ LT_INIT([disable-static win32-dll])
+ # Create libtool early, because it's used in configure
+ LT_OUTPUT
+ 
++# Define _GNU_SOURCE etc. where appropriate, e.g. for strptime() on glibc
++AC_USE_SYSTEM_EXTENSIONS
+ # Make sure we use 64-bit versions of various file stuff.
+ AC_SYS_LARGEFILE
+ 
+diff --git a/gdk/wayland/gdkdevice-wayland.c b/gdk/wayland/gdkdevice-wayland.c
+index 37c6a94..efe413a 100644
+--- a/gdk/wayland/gdkdevice-wayland.c
++++ b/gdk/wayland/gdkdevice-wayland.c
+@@ -15,7 +15,6 @@
+  * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+  */
+ 
+-#define _GNU_SOURCE
+ #include <unistd.h>
+ #include <fcntl.h>
+ #include <errno.h>
+diff --git a/gtk/fnmatch.c b/gtk/fnmatch.c
+index e67052b..87582ca 100644
+--- a/gtk/fnmatch.c
++++ b/gtk/fnmatch.c
+@@ -35,13 +35,6 @@
+ 
+ #include <glib.h>
+ 
+-/* We need to make sure that all constants are defined
+- * to properly compile this file
+- */
+-#ifndef _GNU_SOURCE
+-#define _GNU_SOURCE
+-#endif
+-
+ static gunichar
+ get_char (const char **str)
+ {
+diff --git a/gtk/gtkscalebutton.c b/gtk/gtkscalebutton.c
+index b4bda76..c979f61 100644
+--- a/gtk/gtkscalebutton.c
++++ b/gtk/gtkscalebutton.c
+@@ -36,9 +36,6 @@
+ 
+ #include "gtkscalebutton.h"
+ 
+-#ifndef _WIN32
+-#define _GNU_SOURCE
+-#endif
+ #include <math.h>
+ #include <stdlib.h>
+ #include <string.h>
+diff --git a/gtk/gtksearchenginesimple.c b/gtk/gtksearchenginesimple.c
+index 1475058..4d8ff2f 100644
+--- a/gtk/gtksearchenginesimple.c
++++ b/gtk/gtksearchenginesimple.c
+@@ -21,14 +21,6 @@
+ 
+ #include "config.h"
+ 
+-/* these must be defined even when HAVE_GNU_FTW is not defined
+- * because (really) old versions of GNU libc have ftw.h but do
+- * export ftw() and friends only if _XOPEN_SOURCE and _GNU_SOURCE
+- * are defined. see bug #444097.
+- */
+-#define _XOPEN_SOURCE 600
+-#define _GNU_SOURCE
+-
+ #ifdef HAVE_FTW_H
+ #include <ftw.h>
+ #endif
+diff --git a/modules/printbackends/cups/gtkprintbackendcups.c b/modules/printbackends/cups/gtkprintbackendcups.c
+index a49bb2d..69abd49 100644
+--- a/modules/printbackends/cups/gtkprintbackendcups.c
++++ b/modules/printbackends/cups/gtkprintbackendcups.c
+@@ -17,10 +17,6 @@
+  * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+  */
+ 
+-#ifdef __linux__
+-#define _GNU_SOURCE
+-#endif
+-
+ #include "config.h"
+ #include <ctype.h>
+ #include <unistd.h>
+-- 
+2.1.0
+