[Clang] __builtin_bswapg crashes on bool

[philnik777]

auto test(bool c) {
  return __builtin_bswapg(c);
}

causes Clang to crash with an assertions build: https://godbolt.org/z/7PePeTKGY

This should just be the identity.

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Nikolas Klauser (philnik777)

```c++ auto test(bool c) { return __builtin_bswapg(c); } ``` causes Clang to crash with an assertions build: https://godbolt.org/z/7PePeTKGY

This should just be the identity.