Meta: enable both IPv4 and IPv6 if we're unable to query network interfaces.
Meta: enable both IPv4 and IPv6 if we're unable to query network interfaces.

On systems using systemd, Murmur is often started early, even before
Murmur can query the network interfaces.

This commit adds a fallback, where Murmur will expect such a system to
support both IPv4 and IPv6.

Fixes mumble-voip/mumble#1629
Fixes mumble-voip/mumble#1904

Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble