Only the first entry of config.Net was installed on the wintun adapter,
so dual-stack setups (e.g. net=192.168.123.1/24,fd::2/64) silently
dropped the IPv6 address and IPv6 traffic never worked. Iterate every
configured address and select the netsh context by family (ip for IPv4,
ipv6 for IPv6). A failing address is logged and skipped so one bad
entry no longer aborts the rest or triggers the listenLoop's infinite
recreate-retry. If no address can be configured, return an error
instead of a nil peer IP.
Refs: go-gost/gost#624
ginuerzh
4057ac54b8