Switch to using XFree86 version 4. We do this thru installing the package,

Switch to using XFree86 version 4.  We do this thru installing the package,
so know we have proper PKG registration and dependency information.

This is a WIP for 5.0 DP #1, so it is still rough around the edges and
does not GC the old XFree86 3.3.6 handling stuff that should be GC'ed.
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