Fix typo and small mistake

Author: flip1995

Diff for: src/librustc/lint/context.rs

@@ -417,7 +417,7 @@ impl LintStore {
                             new_name.to_string(),
                         )));
                     }
-                    CheckLintNameResult::Tool(Ok(&ids.0))
+                    CheckLintNameResult::Tool(Err((Some(&ids.0), complete_name)))
                 }
             },
             Some(&Id(ref id)) => {

Diff for: src/librustc/lint/levels.rs

@@ -282,7 +282,7 @@ impl<'a> LintLevelsBuilder<'a> {
                                         .get_lint_level(lint, self.cur, Some(&specs), &sess);
                                 let msg = format!(
                                     "lint name `{}` is deprecated \
-                                     and may not have an effect in the future \
+                                     and may not have an effect in the future. \
                                      Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
                                     name
                                 );