fix freebsd build

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@4650 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch.c

@@ -34,7 +34,7 @@
  */
 
 #ifndef _XOPEN_SOURCE
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #endif
 
 #include <switch.h>