Ticket 80 - Decouple nunc-stans from NSPR
    
    Bug Description:  NSPR uses pthreads underneath so why don't we?
    We also want to use the cleaner inttypes.h. Pthreads is just as
    portable, and cleaner than NSPR
    
    Fix Description:  Replace NSPR in locations except for IO events.
    This includes locks and threads. This has a benefit: We have
    doubled the performance of nunc-stans. We previously saw ~1700
    connections per second, this now exceeds ~3800 per second with
    lock free, and ~1900 with a locked queue.
    
    https://pagure.io/nunc-stans/issue/80
    
    Author: wibrown
    
    Review by: mreynolds (thanks!)