gpg: Do not allow compressed key packets on import.
* g10/import.c (read_block): Bail out on compressed packets. * g10/options.h (COMPAT_COMPR_KEYS): New. * g10/gpg.c (compatibility_flags): Add "compr-keys". * common/util.h (GPG_ERR_UNEXPECTED_PACKET): Add a new replacement code.
Compressed key packets do not make much sense but historically they
were supported. Thus we also add a compatibility flag.
Backported-from-master: 8e529f92219453195073d8a37670dbdf1f3a7e30
- GnuPG-bug-id: T7014