Stop abusing format! macro when construct a String

In these cases for `format!`, we're just constructing a String of the
single argument with no special format.

components/util/opts.rs

@@ -237,7 +237,7 @@ pub fn from_cmdline_args(args: &[String]) -> bool {
     let opt_match = match getopts::getopts(args, opts.as_slice()) {
         Ok(m) => m,
         Err(f) => {
-            args_fail(format!("{}", f).as_slice());
+            args_fail(f.to_string().as_slice());
             return false;
         }
     };