https://cygwin.com/pipermail/cygwin/2022-December/252737.html
If the less is started from non-cygwin shell and window size is
changed, it will hang-up when quitting. The cause of the proglem is
that less uses longjump() in signal handler. If the signal handler
is called while cygwin is acquiring the mutex, cygwin loses the
chance to release mutex. With this patch, the mutex is released
just before calling kill_pgrp() and re-acquired when kill_pgrp()
returns.
Reported-by: Gregory Mason <grmason@epic.com>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>