resolver: fix IPv4/IPv6 on the loopback device
resolver: fix IPv4/IPv6 on the loopback device

My mpc didn't work when I'm offline (i.e. when all my interfaces -
eth0, wlan0 - are down). After some investigation I found that this is
caused by libmpdclient in function resolver_new() in resolver.c:108.

[When you pass the flag AI_ADDRCONFIG to getaddrinfo(), it does not
consider address families on the loopback device.  When run on a
machine without an external network card, just with "lo", it was
unable to look up any address.]

jwise/libmpdclient,sl0th/libmpdclient,cmende/libmpdclient,yusiwen/libmpdclient,cmende/libmpdclient,psych0tik/libmpdclient2,jwise/libmpdclient,sl0th/libmpdclient,psych0tik/libmpdclient2,jagleeso/libmpdclient,sl0th/libmpdclient,jagleeso/libmpdclient,jagleeso/libmpdclient,yusiwen/libmpdclient,yusiwen/libmpdclient,jwise/libmpdclient,cmende/libmpdclient