[compiler-rt] [compiler-rt] Fix definition of `uptr` (and `usize`) on 32-bit Windows (PR #106151)

[Alexander Richardson via llvm-commits]

arichardson wrote:

Hmm interesting, so it sounds like size_t and SIZE_T are different types on Windows. I'll update the patch to address this.

I'm surprised we don't have any builders that were able to catch this.

https://github.com/llvm/llvm-project/pull/106151