cairo: update patch for CVE-2019-6461 with upstream solution

cairo: update patch for CVE-2019-6461 with upstream solution

Upstream went with something slightly different so let's update the
patch so we don't have to carry a patch that isn't going to be merged.

This patch is part of snapshot 1.17.6.

Cc: Quentin Schulz <foss+yocto@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 19eb1e388fbbe5bfb8462710c745f2bb5446b5b5)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>