qemu-socket: Polish errors for connect() and listen() failure

qemu-socket: Polish errors for connect() and listen() failure

connect() doesn't "connect to socket", it connects a socket to an
address and, if it's of type SOCK_STREAM, initiates a connection.
Scratch "to".

listen() does "set socket to listening mode", but it sounds awkward.
Change to "listen on socket".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>