Resolve unnecessary_semicolon pedantic clippy lint

    warning: unnecessary semicolon
       --> benches/rust.rs:103:14
        |
    103 |             };
        |              ^ help: remove
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_semicolon
        = note: `-W clippy::unnecessary-semicolon` implied by `-W clippy::pedantic`
        = help: to override `-W clippy::pedantic` add `#[allow(clippy::unnecessary_semicolon)]`

benches/rust.rs

@@ -100,7 +100,7 @@ mod librustc_parse {
             if let Err(diagnostic) = parser.parse_crate_mod() {
                 diagnostic.cancel();
                 return Err(());
-            };
+            }
             Ok(())
         })
     }