[metacity] build: Use non-deprecated feature test macros

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 56bcf350fb599ec2caf68af4f0f92b1c3999027c
Author: Dmitry Shachnev <mitya57 gmail com>
Date:   Wed Mar 16 22:01:45 2016 +0100

    build: Use non-deprecated feature test macros
    
    _SVID_SOURCE has been deprecated in newer versions of glibc breaking -WError;
    the recommended replacement of _DEFAULT_SOURCE is fairly new, so switch to
    _XOPEN_SOURCE instead.
    
    Based on mutter commits b159d6a5e17219557574defb6c3788d9b0c39757
    and b159d6a5e17219557574defb6c3788d9b0c39757.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=763782

 src/core/delete.c       |    2 +-
 src/core/keybindings.c  |    2 +-
 src/core/main.c         |    2 +-
 src/core/window-props.c |    2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/src/core/delete.c b/src/core/delete.c
index d9a60ab..efc7373 100644
--- a/src/core/delete.c
+++ b/src/core/delete.c
@@ -21,7 +21,7 @@
  */
 
 #define _GNU_SOURCE
-#define _SVID_SOURCE /* for gethostname() */
+#define _XOPEN_SOURCE /* for gethostname() and kill() */
 
 #include <config.h>
 #include "util.h"
diff --git a/src/core/keybindings.c b/src/core/keybindings.c
index 91a5e10..da3b2ac 100644
--- a/src/core/keybindings.c
+++ b/src/core/keybindings.c
@@ -22,7 +22,7 @@
  */
 
 #define _GNU_SOURCE
-#define _SVID_SOURCE /* for putenv() */
+#define _XOPEN_SOURCE /* for putenv() */
 
 #include <config.h>
 #include "keybindings.h"
diff --git a/src/core/main.c b/src/core/main.c
index 85ec424..2e25017 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -40,7 +40,7 @@
  */
 
 #define _GNU_SOURCE
-#define _SVID_SOURCE /* for putenv() and some signal-related functions */
+#define _XOPEN_SOURCE /* for putenv() and some signal-related functions */
 
 #include <config.h>
 #include "main.h"
diff --git a/src/core/window-props.c b/src/core/window-props.c
index 54d3ed2..2387e63 100644
--- a/src/core/window-props.c
+++ b/src/core/window-props.c
@@ -34,7 +34,7 @@
  */
 
 #define _GNU_SOURCE
-#define _SVID_SOURCE /* for gethostname() */
+#define _XOPEN_SOURCE /* for gethostname() */
 
 #include <config.h>
 #include "window-props.h"