Lock Profiling and Lock Order Verification status report #4

[Greg Miller]

Main accomplishments for week 4:

* Implemented pthread_getstatistics_begin_np(),
pthread_getstatistics_next_np(), pthread_getstatistics_end_np()
functions to retrieve profiling stats.
* Implemented pthread_resetstatistics_np() to reset current profiling stats
* Implemented pthread_lockprof_enable_np() and
pthread_lockprof_disable_np() to turn profiling on and off
* Tested and debugged mutex profiling
* Ported mutex profiling code to rwlocks and spinlocks.

With these changes in place, the lock profiling code is now usable.
Further style fixes and comments will be needed later, however.

I'm currently working through the WITNESS code in preparation for lock
order verification coding. For the remainder of the week, I'll
continue that and begin adding libwitness to the build system.