* (mime-pgp-parse-verify-error-for-pgp, mime-pgp-parse-verify-error-for-pgp50,

* (mime-pgp-parse-verify-error-for-pgp, mime-pgp-parse-verify-error-for-pgp50,
mime-pgp-parse-verify-error-for-gpg): New functions.
(mime-verify-application/pgp-signature): Use one of them.
(mime-pgp-parse-verify-error): New macro.
(mime-pgp-check-signature): Returns nil if verify failed under PGP 5.0i.