[clang] [z/OS][Clang] Reland Add wrapper headers to avoid macro name conflicts (#204472) (PR #207420)

[Sean Perry via cfe-commits]

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@@ -0,0 +1,20 @@
+/*===----------------------------- stdlib.h --------------------------------===
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perry-ca wrote:

I hadn't noticed this before, but the stdlib.h wrapper is for the cs builtin functions [PR ](https://github.com/llvm/llvm-project/pull/202362) you also have up for review.  Can you move this header to that PR.

I'll help you create a test case for it as this interacts with the system headers and lit is meant to be independent of system headers.  We'll need to devise a tiny header that mimics the system header like the ones in this PR.

https://github.com/llvm/llvm-project/pull/207420