configure: Define _GNU_SOURCE when checking for setns

glibc defines this function only as gnu extention

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

diff --git a/configure b/configure
index 440facb7f22774a587706c2ff7903e5565a76267..c02753bbdf0cb9fab402fecb2e507e983994b64a 100755 (executable)
--- a/configure
+++ b/configure
@@ -191,6 +191,7 @@ check_ipt_lib_dir()
 check_setns()
 {
     cat >$TMPDIR/setnstest.c <<EOF
+#define _GNU_SOURCE
 #include <sched.h>
 int main(int argc, char **argv)
 {