The SIGWINCH handler triggers breakage in libedit which is hard to fix; see
PR bin/169773.
Also, window size changes while a program is in foreground (and it rather
than sh will receive SIGWINCH) will now be picked up automatically.
Downside: it is now certain that a resize is only processed after pressing
<Enter>. If libedit is fixed, sh will most likely have to be changed also.
PR: bin/180146