This change makes pthread_mutex_lock() as fast as _spinlock() by
default. Thread instability issues on NetBSD have been resolved.
Improvements made to gdtoa thread code. Crash reporting will now
synchronize between threads in a slightly better way.
- Fix Makefile flaking due to ZIPOBJ_FLAGS generation
- Make printf() floating point and gdtoa thread safe
- Polish up the runit / runitd programs some more
- Prune some more makefile dependencies