misc cleanups

[Jamey Sharp]

The following patches should be independent, except that the last three
won't apply cleanly in another order. I think they're mostly pretty
obvious, so I hope they get reviewed. I didn't manage to get them
reviewed around XDS last year, although I don't think I even managed to
send out the patches that I co-authored with Josh...

[PATCH 1/9] dmx: Fix a non-constant printf format string warning.
[PATCH 2/9] dmx: Fix some "no previous prototype" warnings by making
[PATCH 3/9] XineramaInitData ignores its argument. Quit passing one.
[PATCH 4/9] Fix pixmap double-frees on error paths.
[PATCH 5/9] Revert "Bug #6924: Restore the ABI for DrawableRec and
[PATCH 6/9] Eliminate MAXSCREENS-sized CursorScreenKey array.
[PATCH 7/9] xnest: Delete unused nClipRects GC-private field.
[PATCH 8/9] Quit wrapping ChangeClip, CopyClip, and DestroyClip in
[PATCH 9/9] Make GC clientClip always be a region.

Jamey