netns_ifaddrs: fix missing include

src/include/netns_ifaddrs.c

-#define _GNU_SOURCE
 #include <arpa/inet.h>
 #include <errno.h>
 #include <linux/if.h>
@@ -17,6 +16,7 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
+#include "config.h"
 #include "nl.h"
 #include "macro.h"
 #include "netns_ifaddrs.h"

src/include/netns_ifaddrs.h

@@ -11,6 +11,8 @@ extern "C" {
 #include <stdbool.h>
 #include <sys/socket.h>
 
+#include "netns_ifaddrs.h"
+
 struct netns_ifaddrs {
 	struct netns_ifaddrs *ifa_next;