compile with -std=gnu99 and _GNU_SOURCE defined

Should enable _BSD_SOURCE, _SVID_SOURCE, _ATFILE_SOURCE,
_LARGEFILE64_SOURCE, _ISOC99_SOURCE, _XOPEN_SOURCE_EXTENDED,
_POSIX_SOURCE, _POSIX_C_SOURCE, and _XOPEN_SOURCE.

We already require features exposed by some of these defines. Lets
enable them globally to avoid problems caused by the ordering of
includes.

Change-Id: I562c936780c6b1341995281737d4378d8c9b2be7

src/Makefile.am

@@ -5,7 +5,7 @@ noinst_PROGRAMS = unittests unittests-xfr zscanner-tool
 noinst_LTLIBRARIES = libknot.la libknotd.la libknots.la libzscanner.la
 
 # $(YACC) will generate header file
-AM_CFLAGS = -Wall -Ilibknot -DSYSCONFDIR='"$(sysconfdir)"' -DSBINDIR='"$(sbindir)"'
+AM_CFLAGS = -std=gnu99 -D_GNU_SOURCE -Wall -Ilibknot -DSYSCONFDIR='"$(sysconfdir)"' -DSBINDIR='"$(sbindir)"'
 AM_YFLAGS = -d
 libknotd_la_YFLAGS = -pcf_ -d
 libknotd_la_LFLAGS = # TODO: reentrant parser, prefix

src/common/fdset.c

@@ -14,10 +14,6 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE /* Required for RTLD_DEFAULT. */
-#endif
-
 #include <dlfcn.h>
 #include <string.h>
 #include <stdio.h>

src/knot/server/udp-handler.c

@@ -14,10 +14,6 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE /* Required for RTLD_DEFAULT. */
-#endif
-
 #include <dlfcn.h>
 #include <config.h>
 #include <time.h>

src/zscanner/test/tests.c

@@ -14,11 +14,6 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-// strptime under Linux
-#define _XOPEN_SOURCE
-// OpenBSD requires following to disable warning
-#define _XOPEN_SOURCE_EXTENDED 1
-
 #include "zscanner/test/tests.h"
 
 #include <inttypes.h>			// PRIu64