Avoid vfork-related deadlock more cleanly.

Avoid vfork-related deadlock more cleanly.

* callproc.c (child_setup): When the child's exec fails, output
the program name, as that's more useful.  Use O_NONBLOCK to avoid
deadlock.
* process.c (create_process_1): Remove; no longer needed.
(create_process): Remove timer hack; no longer needed, now that
the child avoids deadlock.