suppress warnings about easch <applet>_main() having

no preceding prototype

coreutils/cat.c

@@ -34,6 +34,7 @@ int bb_cat(char **argv)
 	return retval;
 }
 
+int cat_main(int argc, char **argv);
 int cat_main(int argc, char **argv)
 {
 	getopt32(argc, argv, "u");