DRM updates

[Matthew Dillon]

:This is a first patch to start bringing drm in from recent cvs.  This patch
:enables MTRR support, and changes a few structures to get us closer.  It
:doesnt do much, but just turning on MTRR support got me an extra 30 fps in
:glxgears (850 -> 880).
:
:-Craig
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:Craig Dooley                                            craig at xxxxxxxxxx
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    Great work Craig!  Could you redo the __FreeBSD_version checks?  We 
    have a __DragonFly__ predef now which can be used to test for 
    DragonFly builds.  Eventually we are going to remove the __FreeBSD__
    and __FreeBSD_version predefs.

						-Matt