* cygheap.h (class process_lock): New class.

* cygheap.h (class process_lock): New class.
* dtable.h (class dtable): Add class process_lock as a friend.
* dcrt0.cc (get_exit_lock): Delete.
(do_exit): Use process_lock class instead of get_exit_lock.
* exceptions.cc (signal_exit): Ditto.
* pinfo.cc (pinfo::exit): Ditto.
(_pinfo::commune_process): Set process lock around this whole function.
(_pinfo::commune_request): Use process_lock rather than myself.lock.
* pinfo.h (pinfo::_lock): Delete.
(pinfo::initialize_lock): Delete.
(pinfo::lock): Delete.
(pinfo::unlock): Delete.
* winsup.h (get_exit_lock): Delete declaration.