[llvm] [CrossDSO CFI] Make sure __cfi_check has BTI attribute. (PR #131224)

[Teresa Johnson via llvm-commits]

teresajohnson wrote:

Added @vitalybuka and @pcc who are more familiar with CFI. The change looks ok to me but I am not sure whether this should have been handled elsewhere.

https://github.com/llvm/llvm-project/pull/131224