gpg: Be prepared for chosen-prefix SHA-1 collisions in key signatures.

* g10/sig-check.c (check_signature_over_key_or_uid): Reject cewrtain
SHA-1 based signatures.

(cherry picked from c4f2d9e3e1d77d2f1f168764fcdfed32f7d1dfc4)

Adjusted for changed added arguments in a function.

• Signed-off-by: Werner Koch <wk@gnupg.org>