[PATCH] Add locking to mlx(4)

[John Baldwin]

I have patches to add locking to mlx(4) and mark it MPSAFE.  The patches are 
from HEAD but should apply to 8 or 9.  If you test it on 8 or 9 please enable 
INVARIANTS for at least the initial testing.  Thanks.

Given that this is a driver for older hardware, if no one is able to test 
these patches, then I will remove the driver from HEAD after committing these 
fixes.

http://www.FreeBSD.org/~jhb/patches/mlx_locking.patch

-- 
John Baldwin