Fix build on my system and Jedi Outcast support

Hi,
First commit is fixing build on my system (OF macro is an historical curiosity: http://stackoverflow.com/a/7299414).

You may want to use q3_decode_gametype_fallback as default. Or not - it's not my call. Whoever wrote q3_decode_gametype apparently was playing with this idea.
I added it because jk2 server admins set "game" string to whatever they fancy.