FS-6996: #resolve fix define change as of glibc 2.20 for _BSD_SOURCE -> _DEFAULT_SOURCE

libs/libnatpmp/natpmp.c

@@ -15,6 +15,9 @@
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
 #ifdef __linux__
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
 #define _BSD_SOURCE 1
 #endif
 #include <string.h>