machine/mutex.h: Sprinkle sys/types.h, omit machine/lock.h.

Turns out machine/lock.h is not needed for __cpu_simple_lock_t, which
always comes from sys/types.h. And, really, sys/types.h (or at least
sys/stdint.h) is needed for uintN_t and uintptr_t.

Fix userland build by surrounding stuff with #ifdef _KERNEL.

(...Why does this header file get exposed to userland at all?)

Remove __MUTEX_PRIVATE conditional in definition of struct kmutex.

This doesn't buy us anything but the need to hack around it in
ctfmerge to avoid massive duplication of kernel types -- which only
worked for the x86 definition.

This changes only x86 and arm for now, pending compile-testing the
remaining architectures.

Nix now-unused definitions of MUTEX_GIVE/MUTEX_RECEIVE.

branches: 1.6.64; 1.6.68;
A workaround for a bug with some Opteron revisions where locked operations
sometimes do not serve as memory barriers, allowing memory references to
bleed outside of critical sections. It's possible that this is the
reason for pkgbuild's longstanding crashiness.

branches: 1.5.8; 1.5.10; 1.5.14; 1.5.16;
Remove clause 3 and 4 from TNF licenses

branches: 1.4.10; 1.4.12; 1.4.14;
Use atomic_cas_ulong().

branches: 1.3.2; 1.3.4;
make kmutex_t and krwlock_t smaller by killing lock id.
ok'ed by Andrew Doran.

branches: 1.2.4; 1.2.8; 1.2.14; 1.2.24; 1.2.26; 1.2.30; 1.2.32;
Merge newlock2 to head.

branches: 1.1.2;
file mutex.h was initially added on branch newlock2.