define _GNU_SOURCE via autoconf

src/lib/utils/log.cpp

@@ -16,7 +16,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#define _GNU_SOURCE
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
 
 #include "lib/utils/log.h"
 #include <stdlib.h>

src/lib/utils/thread.cpp

@@ -20,10 +20,6 @@
 #  include <config.h>
 #endif
 
-#ifdef HAVE_PTHREAD_SETNAME_NP
-#  define _GNU_SOURCE
-#endif
-
 #include "lib/utils/thread.h"
 #include "lib/utils/clock.h"