Rename the filenames used for the 'win32' package to {lib}HSwin_32{1.o,2.o,.a}
so as to avoid conflicts with the 'Win32' package when installing to a common
library directory on a case-insensitive filesystem (as we do when building
binary dists under Windows.) This fixes the off-the-bat brokenness experienced
by people trying to load the 'Win32' package with ghci-6.4.

Note: package creators may want to make a note of this if they haven't already,
i.e., while the package infrastructure is case-sensitive, it's unsafe to assume
that the underlying filesystem is.

Merge to STABLE.