treewide: cmake buildInputs to nativeBuildInputs, minor cleanups

pkgs/development/tools/xcbuild/default.nix

@@ -47,8 +47,6 @@ in stdenv.mkDerivation {
       --replace "#if HAVE_LIBCOMPRESSION" "#if 0"
   '';
 
-  enableParallelBuilding = true;
-
   # TODO: instruct cmake not to put it in /usr, rather than cleaning up
   postInstall = ''
     mv $out/usr/* $out
@@ -59,7 +57,8 @@ in stdenv.mkDerivation {
 
   cmakeFlags = [ "-GNinja" ];
 
-  buildInputs = [ cmake zlib libxml2 libpng ninja ]
+  nativeBuildInputs = [ cmake ninja ];
+  buildInputs = [ zlib libxml2 libpng ]
     ++ stdenv.lib.optionals stdenv.isDarwin [ CoreServices CoreGraphics ImageIO ];
 
   meta = with stdenv.lib; {