Due to [1], linking with SCTP sometimes does not multi-home correctly.
This is triggered by the rand() on the lines immediately above these.
The connect{} blocks already support an `aftype` parameter to instruct
IRCd to prefer IPv4 or IPv6. This commit additionally ensures that the
other structure is always populated with the other address (if any) if
this parameter is specified.
This will allow SCTP server-linking users to work around the bug and
ensure that it always multi-homes by setting `connect::aftype` to IPv4.
Without this commit, that would cause Solanum to not include the IPv6
addresses (if any) in the connect block in its SCTP setup.
If there isn't a valid IP address in the other sockaddr, this should be
of no consequence, because it will not be used by rb_connect_tcp(), and
both rb_connect_sctp() and rb_sctp_bindx_only() already verify that
there is a valid IP address in the sockaddr before making use of it.
[1] https://marc.info/?l=linux-sctp&m=165684809726472&w=2
a6b99c07d1