Sorry about the megacommit, but this touches on a lot of stuff.

Get rid of XkbFileInfo, which was pretty seriously redundant, and move the
only useful thing it had (defined) into XkbDescRec.  defined will be removed
pretty soon anyway.  Is the compat map pointer non-NULL? Then you have a
compat map, congratulations! Anyhow, I digress.

All functions that took an XkbFileInfoPtr now take an XkbDescPtr, _except_
XkmReadFile, which returns an XkbDescPtr *, because people want to deal in
XkbDescPtrs, not XkbDescRecs.