iptables: declare _GNU_SOURCE to define RTLD_NEXT

This is required to build firewall3 on non-musl systems.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/iptables.h b/iptables.h
index efd7cf3..1d98b76 100644
--- a/iptables.h
+++ b/iptables.h
@@ -19,6 +19,8 @@
 #ifndef __FW3_IPTABLES_H
 #define __FW3_IPTABLES_H
 
+#define _GNU_SOURCE /* RTLD_NEXT */
+
 #include <libiptc/libiptc.h>
 #include <libiptc/libip6tc.h>
 #include <xtables.h>