Move open_fhs from fhandler.h to cygheap.h for easier tracking. Accommodate

Move open_fhs from fhandler.h to cygheap.h for easier tracking.  Accommodate
this change throughout.
* dtable.cc (dtable::add_archetype): Use correct count when iterating through
*active* archetypes.
* dtable.cc (dtable::fixup_after_exec): Close handle if close_on_exec and
archetype exists since archetype currently does not set windows close-on-exec
flag (FIXME).
* fhandler_tty.cc (fhandler_tty_slave::open): Change debugging output slightly.
(fhandler_tty_slave::close): Ditto.
(fhandler_tty_slave::fixup_after_fork): Just report on inherited use counts
since since archetype currently does not set windows close-on-exec flag
(FIXME).
* pinfo.cc (_pinfo::set_ctty): Change debugging output slightly.
* cygheap.cc (cygheap_init): Remove open_fhs accommodation and use count
reporting.
* perthread.h (vfork_save::fhctty): New element.
* perthread.h (vfork_save::open_fhs): New element.
* fork.cc (vfork): Muck around with ctty and open_fhs stuff, both of which are
now saved in the vfork_save structure.