* cygheap.cc (init_cygheap::manage_console_count): Turn console control handler

* cygheap.cc (init_cygheap::manage_console_count): Turn console control handler
on/off depending on whether we have allocated a console or not.
* dcrt0.cc (child_info_fork::fork_retry): Add more potential retry statuses.
(dll_crt0_0): Turn on/off console control depending on whether we have a
controlling tty or not.
* exceptions.cc (init_console_handler): Change BOOL to bool.
* fhandler_console.cc (fhandler_console::need_invisible): Cosmetic change.
* winsup.h (init_console_handler): Reflect argument type change.
* wincap.h (supports_setconsolectrlhandler_null): Remove duplicate capability
throughout.
* wincap.cc: Ditto.