Wireshark-dev: Re: [Wireshark-dev] IMSI Dissection API?
From: Tyson Key <tyson.key@xxxxxxxxx>
Date: Thu, 6 Jan 2011 18:12:04 +0000
Probably bad form to reply to my own post, but I've found that adding " -g -D_U_="__attribute__((unused))"" to the end of my CFLAGS line in my Makefile, without the surrounding quotes makes things build successfully when including epan/dissectors/packet-gsm_map.h.

I hope that helps others.