command: don't allow adding local files on WIN32

There are no unix sockets on WIN32, and therefore no authentication.
WIN32 might have similar capabilities, but until we implement them,
disable that MPD feature.

src/command.c

@@ -451,8 +451,12 @@ handle_add(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 	enum playlist_result result;
 
 	if (strncmp(path, "file:///", 8) == 0) {
+#ifndef WIN32
+		result = PLAYLIST_RESULT_DENIED;
+#else
 		result = playlist_append_file(path + 7, client_get_uid(client),
 					      NULL);
+#endif
 		return print_playlist_result(client, result);
 	}