Bugzilla - Add keyword and remove OS's

[Austin English]

Howdy,

The OS list in bugzilla is a bit excessive. There are 16 OS's that I
think we should remove, as no one is using them (HP-UX has one bug
filed against it, but for all intents and purposes, it's not being
used). Many of these aren't x86, so only could be used for Winelib
anyway.
Mac System 7
Mac System 7.5
Mac System 7.6.1
Mac System 8.0
Mac System 8.5
Mac System 8.6
Mac System 9.x
BSDI
AIX
BeOS
HP-UX
IRIX
Neutrino
OpenVMS
OS/2
OSF/1

While we're at it, I'd like to add PC-BSD and OpenSolaris.

Lastly, how about a compiler keyword, for bugs related to compiler
warnings/errors/etc.?