Cygwin: console: Disable cons_master_thread in win32-input-mode
When win32-input-mode (which is supported by Windows Termainal) is
set by "\033[?9001h", cons_master_thread does not work properly and
consumes larger and larger memory space. This is because sending
event by WriteConsoleInput() is translated into the sequence that
is used by win32-input-mode. Due to this behaviour, write-back
of the INPUT_RECORDs does not work as expected. With this patch,
cons_master_thread is disabled on win32-input-mode where the signal
keys such as Ctrl-C, Ctrl-Z etc. never comes.