Fix author lint and move it back to tests/ui

The author lint is not an internal lint, but a lint that should be eval_always
and also be enabled, when Clippy is distributed through rustup. This adds a
dummy lint clippy::AUTHOR that is eval_always, but not shown in the Clippy
documentation. Similar to the clippy::CTFE lint.

Author: flip1995

clippy_lints/src/utils/author.rs

@@ -7,12 +7,14 @@ use rustc_hir::{
     ExprKind, FnRetTy, HirId, Lit, PatKind, QPath, StmtKind, TyKind,
 };
 use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_session::declare_lint_pass;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol::{Ident, Symbol};
 use std::cell::Cell;
 use std::fmt::{Display, Formatter, Write as _};
 
-declare_lint_pass!(
+// Not using `declare_clippy_lint`, so that no static CLIPPY_CTFE_INFO is created, so this lint
+// doesn't show up in the documentation.
+declare_tool_lint! {
     /// ### What it does
     /// Generates clippy code that detects the offending pattern
     ///
@@ -44,7 +46,15 @@ declare_lint_pass!(
     ///     // report your lint here
     /// }
     /// ```
-    Author => []
+    pub clippy::AUTHOR,
+    Allow,
+    "Ensure CTFE is being made",
+    report_in_external_macro: true,
+    @eval_always = true
+}
+
+declare_lint_pass!(
+    Author => [AUTHOR]
 );
 
 /// Writes a line of output with indentation added

tests/ui-internal/author.rs renamed to tests/ui/author.rs

@@ -1,5 +1,3 @@
-#![warn(clippy::author)]
-
 fn main() {
     #[clippy::author]
     let x: char = 0x45 as char;