* cygheap.cc (init_cygheap::manage_console_count): Revert previous change.
Handle this a different way.
* external.cc (cygwin_internal): Accommodate extra hook_or_detect_cygwin
argument.
* hookapi.cc (cygwin_internal): Fill in subsys variable with the subsystem of
the executable.
* spawn.cc (av::iscui): New variable.
(spawn_guts): Hide window when we don't have a console and this isn't
NT/XP/2003.
(av::fixup): Set iscui flag.
* winsup.h (hook_or_detect_cygwin): Accommodate extra argument.