Recover inner attributes in algebraic data types

[JonathanBrouwer]

Previously, if you'd put an inner attribute in an empty ADT, such as a struct:

struct Test1 {
    #![inline]
}

You'd get the following errors

error: an inner attribute is not permitted in this context
 --> src/lib.rs:5:5
  |
5 |     #![cfg(false)]
  |     ^^^^^^^^^^^^^^
  |
  = note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files
  = note: outer attributes, like `#[test]`, annotate the item following them

error: expected identifier, found `}`
 --> src/lib.rs:6:1
  |
4 | struct Test3 {
  |        ----- while parsing this struct
5 |     #![cfg(false)]
6 | }
  | ^ expected identifier

error: could not compile `rust-test` (lib) due to 2 previous errors

The second error is spurious. It was caused by us only recovering inner attributes just before parsing a field, meaning if we see an inner attribute and recover we expect a field next. This PR fixes that by recovering inner attributes just after the curly brace as well.

[rustbot]

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

cc @fmease

[rustbot]

r? @wesleywiser

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