Rollup merge of #142158 - xizheyin:141617, r=jdonszelmann

Tracking the old name of renamed unstable library features

This PR resolves the first problem of rust-lang/rust#141617 : tracking renamed unstable features. The first commit is to add a ui test, and the second one tracks the changes. I will comment on the code for clarification.

r? `@jdonszelmann`
There have been a lot of PR's reviewed by you lately, thanks for your time!

cc `@jyn514`

compiler/rustc_attr_data_structures/src/stability.rs

@@ -132,6 +132,7 @@ pub enum StabilityLevel {
         /// fn foobar() {}
         /// ```
         implied_by: Option<Symbol>,
+        old_name: Option<Symbol>,
     },
     /// `#[stable]`
     Stable {