[llvm] [cmake] Hardcode some `check_include_file` checks (PR #104706)

[Vlad Serebrennikov via llvm-commits]

Endilll wrote:

> Do you know why are some of these needed in the first place? For example, do we actually supports platforms that don't have errno.h?

Unfortunately, just getting all those older platforms listed in the description running, and testing those headers on them took a lot of time. Yes, I see a potential clean-up after this PR for `#ifdef HAVE_ERRNO_H`, but I don't know for sure if that's still needed.

https://github.com/llvm/llvm-project/pull/104706