UPSTREAM: um: add support for TIF_NOTIFY_SIGNAL

[ Upstream commit a5b3cd32 ]

Wire up TIF_NOTIFY_SIGNAL handling for um.

Cc: linux-um@lists.infradead.org
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Change-Id: Idc702390f1ba7575230aa4c81d27f80088b17afc
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit dc808ffd)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>