upstream: fix bug in HostbasedAcceptedKeyTypes and

PubkeyAcceptedKeyTypes options. If only RSA-SHA2 siganture types were
specified, then authentication would always fail for RSA keys as the monitor
checks only the base key (not the signature algorithm) type against
*AcceptedKeyTypes. bz#2746; reported by Jakub Jelen; ok dtucker

OpenBSD-Commit-ID: 117bc3dc54578dbdb515a1d3732988cb5b00461b
