bugzilla: merge OS X/Windows OS versions

[Austin English]

This was mentioned a while back, though I can't find the reference on
wine-devel, perhaps it was in #winehackers...

Anyway, would anyone be opposed to merging the Mac OS X versions (and
possibly the Windows versions) in the OS field in Bugzilla? We don't
differentiate any other OS, and for Windows, there are very few bugs
filed anyway (mostly against the test suite or building on cygwin).

So, instead of:
Windows 3.1
Windows 95
Windows 98
Windows ME
Windows 2000
Windows NT
Windows XP
Windows Vista
Mac OS X 10.2
Mac OS X 10.3
Mac OS X 10.4
Mac OS X 10.5
Mac OS X 10.6

We'd have:
Windows (All versions)
Mac OS X

I meant to do this a while ago, but forgot, and
http://bugs.winehq.org/show_bug.cgi?id=27930 reminded me