tiff: Exclude CVE-2015-7313 from cve-check

Some fix upstream addresses the issue, it isn't clear which change this was. Our
current version doesn't have issues with the test image though so we can exclude.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 3874da69)
Signed-off-by: Steve Sakoman <steve@sakoman.com>