use _DEFAULT_SOURCE for newer glibc

Newer versions of glibc have moved to _DEFAULT_SOURCE and away from
_BSD_SOURCE.  Trying to use the BSD define by itself leads to warnings
which causes build failures.

BRANCH=none
BUG=None
TEST=precq still works

Signed-off-by: Mike Frysinger <vapier@chromium.org>
Change-Id: Ice24b84dc6a540695fc7b76e8f22a4c85c301976
Reviewed-on: https://chromium-review.googlesource.com/316730
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

util/ec_uartd.c

@@ -11,7 +11,8 @@
  */
 
 /* Force header files to define grantpt(), posix_openpt(), cfmakeraw() */
-#define _BSD_SOURCE
+#define _DEFAULT_SOURCE /* Newer glibc */
+#define _BSD_SOURCE     /* Older glibc */
 #define _XOPEN_SOURCE 600
 /* Force header file to declare ptsname_r(), etc. */
 #ifndef _GNU_SOURCE

util/stm32mon.c

@@ -13,7 +13,8 @@
  */
 
 /* use cfmakeraw() */
-#define _BSD_SOURCE
+#define _DEFAULT_SOURCE /* Newer glibc */
+#define _BSD_SOURCE     /* Older glibc */
 
 #include <arpa/inet.h>
 #include <errno.h>