configure.ac: simplified checks for socket()/getaddrinfo()
configure.ac: simplified checks for socket()/getaddrinfo()

The socket() check fails on mingw32 (probably because autoconf's
prototype is wrong?), but it's safe to say the function is present.
We just need to check if we need -lsocket.

cmende/libmpdclient,psych0tik/libmpdclient2,sl0th/libmpdclient,jagleeso/libmpdclient,jagleeso/libmpdclient,yusiwen/libmpdclient,sl0th/libmpdclient,jwise/libmpdclient,jwise/libmpdclient,OpenInkpot-archive/iplinux-libmpdclient,jagleeso/libmpdclient,sl0th/libmpdclient,yusiwen/libmpdclient,yusiwen/libmpdclient,OpenInkpot-archive/iplinux-libmpdclient,jwise/libmpdclient,cmende/libmpdclient,cmende/libmpdclient,psych0tik/libmpdclient2