remove unnecessary trailing semicolon from bootstrap

src/bootstrap/config.rs

@@ -334,7 +334,7 @@ fn do_merge<T: Merge>(x: &mut Option<T>, y: Option<T>) {
                     *x = Some(new);
                 }
             }
-        };
+        }
         do_merge(&mut self.build, build);
         do_merge(&mut self.install, install);
         do_merge(&mut self.llvm, llvm);