fix Sys.command on windows once again (see https://github.com/HaxeFoundation/haxe/commit/41cf47f215f9b2c9e9d0ff03c415204c62273a51#commitcomment-8443045)

std/neko/_std/Sys.hx

@@ -113,6 +113,7 @@
 			for( a in args )
 				cmd += " "+escapeArgument(a, win);
 		}
+		if (win) cmd = '"$cmd"';
 		return sys_command(untyped cmd.__s);
 	}