Add strictness check for '-n'.

src/options/view.rs

@@ -85,7 +85,7 @@ impl Mode {
         // user about flags that won’t have any effect.
         if matches.is_strict() {
             for option in &[ &flags::BINARY, &flags::BYTES, &flags::INODE, &flags::LINKS,
-                             &flags::HEADER, &flags::BLOCKS, &flags::TIME, &flags::GROUP ] {
+                             &flags::HEADER, &flags::BLOCKS, &flags::TIME, &flags::GROUP, &flags::NUM_UGID ] {
                 if matches.has(option)? {
                     return Err(OptionsError::Useless(*option, false, &flags::LONG));
                 }