Atomic operations patch

[John Baldwin]

I have some cleanups for the atomic operations that fixes incorrect use of the 
"+m" constraint and changes the atomic_foo_ptr() operations to operate on 
uintptr_t's rather than void *'s to make it simpler to implement.  Patch is 
at http://www.FreeBSD.org/~jhb/patches/atomic.patch  It's already tested on 
alpha, i386, and sparc64.  Please let me know how it goes for the other 
archs.  Thanks,

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org