Revamp suspend and resume. While I'm here add pthread_suspend_all_np()
and pthread_resume_all_np(). These suspend and resume all threads except
the current thread, respectively. The existing functions pthread_single_np()
and pthread_multi_np(), which formerly had no effect, now exhibit the same
behaviour and pthread_suspend_all_np() and pthread_resume_all_np(). These
functions have been added mostly for the native java port.

Don't allow the uthread kernel pipe to use the same descriptors as
stdio. Mostily submitted by Oswald Buddenhagen <ossi@kde.org>.

Correct some minor style nits.