[compiler-rt] [CompilerRT] Add numerical sanitizer (PR #94322)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I am sorry that I did not notice this patch but I feel sad that this has been committed with many style issues. I fully support numerical sanitizer but I think we really should do a better code style job for posterity.  Created #96142

https://github.com/llvm/llvm-project/pull/94322