compat-util: add _DEFAULT_SOURCE define

glibc has deprecated the use of _BSD_SOURCE define

  warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"

To make it easier to maintain a cross platform source code, that
warning can be suppressed by _DEFAULT_SOURCE.

Define both _BSD_SOURCE and _DEFAULT_SOURCE to clean-up the build.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-compat-util.h

@@ -82,6 +82,7 @@
 #define _ALL_SOURCE 1
 #define _GNU_SOURCE 1
 #define _BSD_SOURCE 1
+#define _DEFAULT_SOURCE 1
 #define _NETBSD_SOURCE 1
 #define _SGI_SOURCE 1