* sigproc.cc (wait_sig): Remove unneeded for loop iteration.

* sigproc.cc (wait_sig): Remove unneeded for loop iteration.
* exceptions.cc (interrupt_setup): Don't set signal mask here or races occur
with main thread.  Set it in sigdelayed instead.
(sigreturn): Reflect change in stack order of ebp and flags.
(sigdelayed): Set stack frame correctly.  Call set_process_mask here with flags
for last trapped signal.
(signal_dispatch): Add newmask.
* sigproc.cc (wait_sig): Eliminate ill-considered attempt to halt looping
signal processors.