openvpn: T4679: Fix incorrect verify local and remote address

In the OpenVPN site-to-site config we can use IPv6 peers
without IPv4 configurations but "verify()" checks also local and
remote IPv4 addresses that in this case will be empty lists
For example:

set interfaces openvpn vtun2 local-address 2001:db8::1
set interfaces openvpn vtun2 remote-address 2001:db8::2

Check in the commit (v4loAddr == v4remAddr) <= both empty lists
commit
DEBUG: [] == [] or ['2001:db8::2'] == []

So we should also check v4loAddr, v4remAddr, v6loAddr, v6remAddr
are not empty