Guarantee entry->other is set when calling put_connected_peers

Guarantee entry->other is set when calling put_connected_peers

Given the original intent of entry->host, the check for DoS attacks, it
can happen that this value remains NULL when an entry is created. This
is particularly awkward if put_connected_peers is called to check if a
connection to a given peer already exists, since it takes the address
family into consideration (git commit b74219d0) which is gleaned from
entry->host.
This patch guarantees that entry->other is a clone of host before
put_connected_peers is called.