add an include guard...

comms.h

@@ -24,6 +24,9 @@
  *
  */
 
+#ifndef __COMMS_H__
+#define __COMMS_H__ 1
+
 #include <sys/types.h>
 #include <stdint.h>
 
@@ -94,3 +97,5 @@ size_t _comms_state_size();
 
 int comms_init(struct comms_state *, process_msgfunc_t, struct pktbuf *, struct pktbuf *, struct pktbuf *);
 void comms_process(struct comms_state *, struct pktbuf, struct pktbuf *);
+
+#endif /* __COMMS_H__ */