ls: avoid string allocation for indicator char

Author: sylvestre

src/uu/ls/src/ls.rs

@@ -3437,7 +3437,8 @@ fn display_item_name(
         };
 
         if let Some(c) = char_opt {
-            name.push(OsStr::new(&c.to_string()));
+            let mut buf = [0u8; 4];
+            name.push(OsStr::new(c.encode_utf8(&mut buf)));
         }
     }