[PATCH] Improve adbe.pkcs7.sha1 signature verification

[PATCH] Improve adbe.pkcs7.sha1 signature verification

For PDF signatures with SubFilter == adbe.pkcs7.sha1, we only
compared hash values and never actually checked SignatureValue
within SignerInfo.

Fix bugs introduced by 055fd58711d57af4d96214aebd71b713303d5527 and
e58ed17e35989350afe3e9fd77b24515df782eac by verifying the actual
(public-key) signature after the hash values compare equal.

Change-Id: I5fa3d60df214cc5efedd1c0eba6cf1b9faf05360
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/183059
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins
(cherry picked from commit 9f687b06fc25156a2a3f4d688b56542612995aa9)

Gbp-Pq: Name Improve-adbe.pkcs7.sha1-signature-verification.diff