gpg: Import only packets which are allowed in a keyblock.
* g10/import.c (valid_keyblock_packet): New. (read_block): Store only valid packets.
A corrupted key, which for example included a mangled public key
encrypted packet, used to corrupt the keyring. This change skips all
packets which are not allowed in a keyblock.
(cherry-picked from commit f795a0d59e197455f8723c300eebf59e09853efa)
- GnuPG-bug-id: T1455