* exceptions.cc (setup_handler): Always relinquish lock after we've

* exceptions.cc (setup_handler): Always relinquish lock after we've
interrupted.
* fhandler.cc: Move pipe methods to pipe.cc.
* fhandler.h (fhandler_pipe): Add new methods.
* fork.cc (sync_with_parent): Make error messages more informative.
* pipe.cc (fhandler_pipe::fhandler_pipe): Move here from fhandler.cc.
(fhandler_pipe::lseek): Ditto.
(fhandler_pipe::set_close_on_exec): New method.
(fhandler_pipe::read): Ditto.
(fhandler_pipe::close): Ditto.
(fhandler_pipe::dup): Ditto.
(make_pipe): Create the guard mutex on the read side of the pipe.
* select.cc (peek_pipe): Use guard_mutex to discover if we have the right to
read on this pipe.
(fhandler_pipe::readh_for_read): Pass the read pipe guard mutex to peek_pipe.
* syscalls.cc (_read): Always detect signal catchers, for now.
* debug.cc (makethread): Eliminate hack to make thread inheritable.
* sigproc.cc (subproc_init): Don't use hack to make thread inheritable.