Count unsafe operations and macro calls once towards the innermost unsafe block

[samueltardieu]

changelog: [multiple_unsafe_ops_per_block]: count unsafe operations only towards the innermost unsafe block

Fixes #16116

r? Jarcho

[github-actions]

Lintcheck changes for 181cb9c

Lint	Added	Removed	Changed
clippy::multiple_unsafe_ops_per_block	0	287	55

This comment will be updated if you push new changes

[Jarcho]

The actual issue is nested unsafe blocks, not macros. I feel like we should be skipping them.

unsafe f1() {}
unsafe f2() {}

fn f3() {
  unsafe {
    f1();
    unsafe { f2(); }
  }
}

This only has one unsafe operation in each block, just one of them happens to be nested in another.

---

We should still be considering a macro call to be a single thing. A macro expanding to multiple unsafe calls without an unsafe block shouldn't trigger the lint.

[samueltardieu]

Done.