terminal: Fix unintended fallthrough to cursor restore

terminal: Fix unintended fallthrough to cursor restore

ef57a9b788 added support for window operations such as reporting the
title in escape mode. It implemented this by which-window-op case,
inside the existing which-escape-code case. Whilst it would break out of
the former window-op case, it never broke out of the latter escape-code
case. This would lead to window ops (such as reporting title) falling
through to restoring the saved cursor position.

This doesn't seem at all right, and also fixes a warning with GCC 8.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>