dragdrop: use "dragon-drop" if it exists
dragdrop: use "dragon-drop" if it exists

to avoid name conflict some distros renamed dragon to `dragon-drop`
https://github.com/mwh/dragon/issues/17#issuecomment-889878960

jarun/noice,jarun/noice,jarun/nnn,jarun/nnn,jarun/nnn,jarun/nnn