* sigproc.cc (pending_signals): Make static.
(wait_sig): Use defined values rather than integers for rc. Never scan both
todo arrays as this could cause hangs if signals arrive from two different
sources. Rename saw_pending_signals to saw_failed_interrupt. Exit loop when
signal found. Enter low-priority sleep, if necessary, after finished
signalling completion. Set pending_signals when blocked
(from Pierre Humblet).