Warning about _BSD_SOURCE being deprecated in favor of _DEFAULT_SOURCE
breaks build with -Werror -Wall

--- configure.ac
+++ configure.ac
@@ -1240,9 +1240,12 @@
 		CFLAGS=$CFLAGS$efl
 		AC_MSG_CHECKING([if DNS resolver is re-entrant])
 		AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
+				#pragma GCC diagnostic push
+				# pragma GCC diagnostic warning "-Wcpp"
 				#define _BSD_SOURCE
 
 				#include <sys/types.h>
+				#pragma GCC diagnostic pop
 				#include <netinet/in.h>
 				#include <arpa/inet.h>
 				#include <arpa/nameser.h>
--- configure
+++ configure
@@ -8390,9 +8390,12 @@
 		cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+				#pragma GCC diagnostic push
+				# pragma GCC diagnostic warning "-Wcpp"
 				#define _BSD_SOURCE
 
 				#include <sys/types.h>
+				#pragma GCC diagnostic pop
 				#include <netinet/in.h>
 				#include <arpa/inet.h>
 				#include <arpa/nameser.h>