pthread_kill prototype

[Robert Collins]

Chris,
  what was the verdict on fixing this? pthread_kill is protoyped (and
implemented) incorrectly in pthread.h & thread.cc (conflicts with
newlibs sys/signal.h). Looking at doco on the web, the correct answer is
to change thread.cc, but that will break binary compatibility.

P.S. I have the rewritten pthreads code fully functional and I've
updated the sched* stuff so I can send in a patch for the lot real soon
now.

Rob