HEADS UP: threadlock going in, likely tonight.

[Jeff Roberson]

This has been up for review and testing for some time.  I think it's ready 
for prime-time.  Only one new bug came up over the weekend and I believe I 
have that fixed.

I'm going to commit the patch in stages but the tree will not be 
functional in between.  I'm not able to break it down into several 
functional steps but I want to leave meaningful commit messages in several 
files.

I will send out one more mail when I start and another when I'm done.

Thanks,
Jeff