fix compiler warnings due to deprecated _BSD_SOURCE

With glibc 2.20 (and newer), defining _BSD_SOURCE (only)
will now generate compiler warnings similar to:

/usr/include/features.h:148:3: warning: #warning "_BSD_SOURCE
and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" [-Wcpp]

See the glibc 2.20 release notes, https://lwn.net/Articles/611162/.

This patch adds the required _DEFAULT_SOURCE.

Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>

fel.c

@@ -16,6 +16,8 @@
  */
 
 /* Needs _BSD_SOURCE for htole and letoh  */
+/* glibc 2.20+ also requires _DEFAULT_SOURCE */
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 #define _NETBSD_SOURCE
 

phoenix_info.c

@@ -16,6 +16,8 @@
  */
 
 /* Needs _BSD_SOURCE for htole and letoh  */
+/* glibc 2.20+ also requires _DEFAULT_SOURCE */
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 
 #include <stdio.h>

pio.c

@@ -18,6 +18,8 @@
  */
 
 /* needs _BSD_SOURCE for htole and letoh  */
+/* glibc 2.20+ also requires _DEFAULT_SOURCE */
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE
 
 #include <errno.h>