cpos: use mpd_recv_pair_named() to obtain the song id
cpos: use mpd_recv_pair_named() to obtain the song id

This allows us to eliminate the whole loop.

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