relay: Don't fail if AF_INET6 family is not supported
Someone on tor-relays@ reported that when going from 044 to 045, their config failed to work:
ORPort 587 DIRPORT 995
[notice] Opening OR listener on 0.0.0.0:587 [notice] Opened OR listener connection (ready) on 0.0.0.0:587 [notice] Opening OR listener on [::]:587 [warn] Socket creation failed: Address family not supported by protocol [notice] Opening Directory listener on 0.0.0.0:995 [notice] Closing partially-constructed OR listener connection (ready) on 0.0.0.0:587 [notice] Closing partially-constructed Directory listener connection (ready) on 0.0.0.0:995
We should probably not fail this in that implicit case for IPv6 if the address is not supported.