Make the network headers compile standalone.

Bug: http://b/28067717
Change-Id: I0f69c6cba0eb0df2fe68f458ba5aa81fe8e6434c
diff --git a/libc/include/net/if_ieee1394.h b/libc/include/net/if_ieee1394.h
index 5a61581..2f8a7c3 100644
--- a/libc/include/net/if_ieee1394.h
+++ b/libc/include/net/if_ieee1394.h
@@ -39,6 +39,8 @@
 #ifndef _NET_IF_IEEE1394_H_
 #define _NET_IF_IEEE1394_H_
 
+#include <sys/types.h>
+
 /* hardware address information for arp / nd */
 struct ieee1394_hwaddr {
 	u_int8_t	iha_uid[8];		/* node unique ID */