gpg: New options --show-session-hash and --show-only-session-hash.
* g10/options.h (opt): Add field show_session_hash. * g10/gpg.c (oShowOnlySessionHash,oShowSessionHash): New. (opts): Add options. (main): Set flags. * common/status.h (STATUS_SESSION_HASH): New. * g10/decrypt-data.c (decrypt_data): Emit new status code. Make opt.show_only_session_key work for the new options.