[PATCH xserver 0/8] Use a separate thread for input [v2]

[Keith Packard]

This is the second version of this series, the big change it to switch
to a counting mutex using a thread-local variable. This makes the
existing input_lock/input_unlock stuff 'just work' as the old
OsBlockSIGIO stuff had a counter too. There's one change in locking;
injected xkb events were being processed with the lock released, which
isn't consistent with the other event processing, so I changed it to
match.

I've also removed the DRI1 changes; they're not germane to this issue
and can be addressed when someone wants to try removing that in the
future.

Thanks for the review so far; I think I'm ready to try this on my main
machine and see how I fare.

-keith