gpg,sm: Error out on compliance mismatch while decrypting.
* g10/pubkey-enc.c (get_session_key): Bail out if the algo is not allowed in the current compliance mode. * sm/decrypt.c (gpgsm_decrypt): Ditto.
The idea here is that the owner of the key created a non-compliant key
and later receives a mail encrypted to that key. The sender should
have checked this key too but we can't guarantee that. By hard
failing here the owner of the key will notice that he had created a
non-compliant key and thus has a chance to generate a new compliant
key. In case the compliant criteria changes and the owner wants to
decrypt an old message he can still switch gpg to another compliant