Provide key preparsing in the keyring so that we can make preparsing
mandatory.  For keyrings, however, only an empty payload is permitted.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NSteve Dickson <steved@redhat.com>
Acked-by: NJeff Layton <jlayton@primarydata.com>