in forked process.
(interruptible): Flag as interruptible when running in main process module.
(interrupt_setup): Save return address and address of return address.
(signal_fixup_after_fork): New function. Uses above two values to restore
proper behavior to forked process.
(interrupt_on_return): Pass return address address to interupt_setup.
(interrupt_now): Pass NULL for return address address to interrupt_setup.
* fork.cc (fork): Call signal_fixup_after_fork.
* shared.h: Lint cleanups.
* winsup.h: Ditto.
interruptible.
(call_handler): Avoid suspending a thread if it owns a mutex. Only set
signal_arrived if the thread was actually interrupted.
(events_init): Initialize module information needed by interruptible().
(sigdelayed): Don't call sig_dispatch_pending since it could screw up
* init.cc (dll_entry): Record module handle of main for use by interruptible().
(proc_subproc): Reorganize handling of terminated child so that the bulk of the
processing comes from the signal thread.
(wait_sig): Force processing of waiting threads if SIGCHLD is not processed.
* sync.cc (muto::release): Set tid == 0 after lock is released or signal
processor will be confused.
