hello-wayland: depend on wayland-scanner

Otherwise, wayland-scanner would be picked up from the wayland in
buildInputs, which isn't cross-friendly and will stop working when we
split wayland-scanner into a separate package.

pkgs/applications/graphics/hello-wayland/default.nix

@@ -15,7 +15,6 @@ stdenv.mkDerivation {
   };
 
   separateDebugInfo = true;
-
   depsBuildBuild = [ pkg-config ];
   nativeBuildInputs = [ imagemagick pkg-config wayland-scanner ];
   buildInputs = [ wayland wayland-protocols ];