0.9.1.59:

0.9.1.59:
        merged most of the pthreads stuff from amd64-pthread-branch except
        the amd64 part, plus:
        * in the runtime thread_kill, thread_sigmask, thread_self
          stand for pthread_kill or kill, sigprocmaks or
          pthread_sigmask, and pthread_self or getpid respectively
          controlled by the sb-thread feature
        * fixed recursive get on session-lock that happened when a gc
          interrupting get-foreground reaped a thread
        * fixed sigint handling: removed broken (by pthread signal
          handling semantics) sigint enable/disable machinery in favor
          of sigint-%break looking up the foreground thread and
          interrupting it, which is itself racy :-(.
        * numerous fixes for interrupt-thread
        * threads block signals until they are set up properly
        * removed suspend-thread, resume-thread
        * destroy-thread is now equivalent to terminate-thread.