Set inhibit-compacting-font-caches non-nil on MS-Windows

[Eli Zaretskii]

I think we should make this variable non-nil by default on
MS-Windows.

There are quite a few bug reports in the bug DB which all complain
about slow redisplay on MS-Windows, and were resolved by setting this
variable non-nil.  So it sounds like on MS-Windows the compacting of
the font caches is not a good idea (the original code was written to
fix a problem observed on X).

Any objections/comments?