Fix build with broadcom arm compiler.

--- bridge2/libbridge/libbridge.h	2011-03-28 17:52:54.000000000 -0700
+++ bridge-utils-1.5/libbridge/libbridge.h	2015-09-17 11:29:46.263737398 -0700
@@ -20,6 +20,7 @@
 #define _LIBBRIDGE_H
 
 #include <sys/socket.h>
+#include <netinet/in.h>
 #include <linux/if.h>
 #include <linux/if_bridge.h>