Unmanaged implementation of spin free locks.

The commit addresses race issues between the waiting on the lock semaphore and the release of the lock. The entry count and the owner field are grouped together into the status field. Accesses to it are done using atomic cas operations so threads aren't lost waiting for release on the lock semaphore.
[amd64] Enable the monitor enter/exit fastpaths.
[x86] Enable the monitor enter/exit fastpaths.
[x86] Add monitor enter v4 fastpath.
[amd64] Add monitor enter v4 fastpath.