Fix#193892.
This is found during libc++ bringing up process. This patch:
- implement recursive mutex support for real.
- fix the issue that pthread mutex initializer and public mutex
interface misalign with internal representation. this was the root cause
that hangs the libc++ test as padding bytes effectively pollute the
futex state if default initializer was used.
- additionally, we changed the field to bitfield to allow encoding more
data. (e.g. the error checking flag that is not yet added). timed bit is
removed as we always support it anyway. PI bit is added instead.
b7d6438450