Optimized fast-paths for rw_enter() / rw_tryenter() / rw_exit().

Largely eliminate the MD rwlock.h header file.

This was full of definitions that have been obsolete for over a
decade. The file still remains for __HAVE_RW_STUBS but that's all.
Used only internall

Largely eliminate the MD rwlock.h header file.

This was full of definitions that have been obsolete for over a
decade. The file still remains for __HAVE_RW_STUBS but that's all.
Used only internally in kern_rwlock.c now, not by <sys/rwlock.h>.

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Remove clause 3 and 4 from TNF licenses

make kmutex_t and krwlock_t smaller by killing lock id.
ok'ed by Andrew Doran.

Merge newlock2 to head.