idle.h: fix a typo ("receivedd")
idle.h: fix a typo ("receivedd")

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