[compiler-rt] [compiler-rt] fix gcc 12 support by removing enum-type-specifier (PR #165034)

[Saleem Abdulrasool via llvm-commits]

compnerd wrote:

> > This isn't fine sadly - the signedness is platform specific. This needs to be preserved. I think that requiring GCC 7+ is acceptable.
> 
> Sorry if I didn't make it clear. I am trying to say that the enum doesn't need to be `unsigned int`. It used to be just `int` before #164713. This code used enum-type-specifier which is going to push GCC requirement to 13+ from the current 7+.

But it does. The recent change changed the struct member from `unsigned int` to the enumerator type. If you want to make this ABI compliant, I think that we should revert the change to the struct to use the `unsigned int`.

https://github.com/llvm/llvm-project/pull/165034