* child_info.h (CURR_CHILD_INFO_MAGIC): Reset.

* child_info.h (CURR_CHILD_INFO_MAGIC): Reset.
(child_info::rd_proc_pipe): Declare new field.
(child_info::wr_proc_pipe): Ditto.
(child_info::prefork): Declare new function, derived from previous pinfo
version.
* dcrt0.cc (child_info_fork::handle_fork): Close previous wr_proc_pipe when
appropriate and assign new one from passed-in child_info block.
(child_info_spawn::handle_spawn): Assign our wr_proc_pipe handle from passed-in
child_info block.
* fork.cc (child_info::prefork): Define new function.
(frok::child): Clear rd_proc_pipe and wr_proc_pipe so they will not be closed
by the child_info destructor.
(frok::parent): Use child_info prefork handling, outside of retry loop.  Set
rd_proc_pipe in child's pinfo after successful CreateProcess.  Eliminate
postfork call.
* globals.cc (my_wr_proc_pipe): Define/declare new variable.
* pinfo.cc (pinfo::pending_rd_proc_pipe): Delete.
(pinfo::pending_wr_proc_pipe): Ditto.
(pinfo::prefork): Ditto.
(pinfo::postfork): Ditto.
(pinfo::postexec): Ditto.
(pinfo::wait): Assume that rd_proc_pipe is set up correctly prior to call.
(_pinfo::alert_parent): Replace "wr_proc_pipe" with "my_wr_proc_pipe".
* pinfo.h (_pinfo::_wr_proc_pipe): Delete declaration.
(_pinfo::set_rd_proc_pipe): Define new function.
(pinfo::pending_rd_proc_pipe): Delete declaration.
(pinfo::pending_wr_proc_pipe): Ditto.
(pinfo::prefork): Ditto.
(pinfo::postfork): Ditto.
(pinfo::postexec): Ditto.
(pinfo::wr_proc_pipe): Ditto.
* sigproc.cc (child_info::child_info): Clear rd_proc_pipe and wr_proc_pipe.
(child_info::cleanup): Close rd_proc_pipe and wr_proc_pipe if necessary.
(child_info_fork::child_info_fork): Set forker_finished to NULL by default.
(child_info_spawn::child_info_spawn): Use my_wr_proc_pipe rather than
myself->wr_proc_pipe.
(child_info::sync): Ditto.
(child_info_spawn::cleanup): Call child_info::cleanup.
* spawn.cc (child_info_spawn::worker): Remove call to myself.prefork().  Set
wr_proc_pipe when execing or set up new rd_proc_pipe/wr_proc_pipe via
child_info::prefork when spawning.  Remove call to pinfo::postexec.  Set
rd_proc_pipe in child pinfo when spawning.  Use my_wr_proc_pipe rather than
myself->wr_proc_pipe.  Remove call to postfork.