[clang] crash when using `[[clang::musttail]]` on function marked `[[noreturn]]`

[philnik777]

[[noreturn]] void throw_int() {
  throw int();
}

void throw_int_wrapper() {
  [[clang::musttail]] return throw_int();
}

causes clang to crash: https://godbolt.org/z/vvPh9KGGn

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Nikolas Klauser (philnik777)

```c++ [[noreturn]] void throw_int() { throw int(); }

void throw_int_wrapper() {
[[clang::musttail]] return throw_int();
}

causes clang to crash: https://godbolt.org/z/vvPh9KGGn
</details>

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Nikolas Klauser (philnik777)

```c++ [[noreturn]] void throw_int() { throw int(); }

void throw_int_wrapper() {
[[clang::musttail]] return throw_int();
}

causes clang to crash: https://godbolt.org/z/vvPh9KGGn
</details>