gpg: Add some asserts.
* g10/build-packet.c (ctb_new_format_p): New function. (ctb_pkttype): New function. (do_user_id): Add some asserts. (do_key): Likewise. (do_symkey_enc): Likewise. (do_pubkey_enc): Likewise. (do_plaintext): Likewise. (do_encrypted): Likewise. (do_encrypted_mdc): Likewise. (do_compressed): Likewise. (do_signature): Likewise. (do_signature): Likewise. (write_header2): Likewise.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>