* fhandler.h (fhandler_tty_master::fixup_after_fork): Remove declaration.

* fhandler.h (fhandler_tty_master::fixup_after_fork): Remove declaration.
(fhandler_tty_master::fixup_after_exec): Ditto.
* fhandler_tty.cc (fhandler_tty_master::init): Fix so that children do not
inherit master tty handles.
(fhandler_tty_master::fixup_after_fork): Remove, since it was never used.
(fhandler_tty_master::fixup_after_exec): Ditto.
* pinfo.cc (_pinfo::set_ctty): Increment open_fhs when ctty is set.
* cygheap.cc (cygheap_init): Ditto.
* syscalls.cc (setsid): *Always* call close on opened ctty since the archetype
is associated with the ctty and it counts as an opened handle.
* tty.cc (tty::common_init): Don't protect input/output mutex since it confuses
subsequent fork/execs when CYGWIN=tty.