Checked in bz2 changes to setup.cc

[Christopher Faylor]

I've checked in the bz2 additions to setup.exe.  They were fairly major
so I'm not 100% certain that everything is ok.

I created a winsup/bz2lib rather than a winsup/cinstall/bz2lib since I
plan on using the bz2 library for "other stuff" down the road.

So, if you have stuff checked out via CVS, you'll have to cd to the
winsup directory and type 'cvs update -d'.

cgf