[clang] [clang][analyzer] Add note tags to alpha.unix.BlockInCriticalSection (PR #80029)

[Balázs Kéri via cfe-commits]

balazske wrote:

I think we could get a note at the first `lock` call in this code, this behavior is not entirely correct:
```
void test() {
  std::mutex m;
  m.lock();
  m.unlock();
  m.lock();
  sleep(3);
  m.unlock();
}
```

https://github.com/llvm/llvm-project/pull/80029