Adapted POSIX feature defines

examples/client_subscription_loop.c

@@ -2,7 +2,7 @@
  * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
 
 /* Enable POSIX features */
-#ifndef _XOPEN_SOURCE
+#if !defined(_XOPEN_SOURCE) && !defined(_WRS_KERNEL)
 # define _XOPEN_SOURCE 600
 #endif
 #ifndef _DEFAULT_SOURCE