Rollup merge of #48317 - ExpHP:unused-unsafe-is-no-fn, r=estebank

unused_unsafe: don't label irrelevant fns

Fixes #48131

Diagnostic bugfix to remove an errant note.  Stops the search for an enclosing unsafe scope at the first safe fn encountered.

```rust
pub unsafe fn outer() {
    fn inner() {
        unsafe { /* unnecessary */ }
    }

    inner()
}
```

**Before:**

```
warning: unnecessary `unsafe` block
 --> src/main.rs:3:9
  |
1 | pub unsafe fn outer() {
  | --------------------- because it's nested under this `unsafe` fn
2 |     fn inner() {
3 |         unsafe { /* unnecessary */ }
  |         ^^^^^^ unnecessary `unsafe` block
  |
  = note: #[warn(unused_unsafe)] on by default
```

**After:**

```
warning: unnecessary `unsafe` block
 --> src/main.rs:3:9
  |
3 |         unsafe { /* unnecessary */ }
  |         ^^^^^^ unnecessary `unsafe` block
  |
  = note: #[warn(unused_unsafe)] on by default
```

0 files changed, 0 insertions, 0 deletions