[compiler-rt] [compiler-rt] fix gcc <13 support by removing enum-type-specifier (PR #165034)

[Yuxuan Chen via llvm-commits]

yuxuanchen1997 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 not before https://github.com/llvm/llvm-project/pull/164713. This code used enum-type-specifier which is going to push GCC requirement to 13+ from the current 7+. 

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