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

[Sean Perry via llvm-commits]

perry-ca wrote:

The list of header not found for z/OS is:
- <link.h>
- <mach/mach.h>
- <malloc/malloc.h>
- <sys/param.h>
- <sysexits.h>


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