+ define COMPRESSMANCMD as imake seems to expect this to be defined
(FreeBSD define this in {$X11BASE}/lib/X11/config/FreeBSD.cf)
+ when preprocessing to set the correct prefix, use LOCALBASE rather
than PREFIX, as USE_IMAKE will set PREFIX by default
+ eliminate an unnecessary temporary file when preprocessing to set
the correct prefix.
Add a pre-process stage (at pre-configure time) to change hard-coded
/usr/local into ${PREFIX}. Revert the patches I'd previously changed
to the default ${PREFIX} to be /usr/local once again, so that the
pre-processing will work.
