Rollup merge of #60959 - petrochenkov:sassert, r=estebank

rustc: Improve type size assertions

Now they
- Tell what the new size is, when it changes
- Do not require passing an identifier

```
   ::: src\libsyntax\parse\token.rs:223:1
    |
223 |    static_assert_size!(Token, 123);
    |    -------------------------------- in this macro invocation
    |
    = note: expected type `[(); 123]`
               found type `[(); 16]`
```

diff --cc src/librustc/hir/mod.rs
Simple merge

diff --cc src/librustc/ty/mod.rs
Simple merge

diff --cc src/librustc/ty/sty.rs
Simple merge