[clang] [llvm] [SystemZ] Do not extend integer arguments in z/OS XPLINK64 ABI (PR #206833)

[Zibi Sarbinowski via llvm-commits]

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zibi2 wrote:

Revert only [3762fc467a9192d317a97b5d69a4702cd30753a3](vscode-webview://0q47aeauilrahkbfc8c20h9i3bte43ko53uiqslgmbiqj8n6sd85/up0/llvm-project).

Keep [b17680d9a079fb5fff0c62f97928a34c1d3a7fe4](vscode-webview://0q47aeauilrahkbfc8c20h9i3bte43ko53uiqslgmbiqj8n6sd85/up0/llvm-project), since reverting it breaks z/OS builtins tests; one representative failure is discussed in [PR #206833 comment discussion_r3669001807](https://github.com/llvm/llvm-project/pull/206833#discussion_r3669001807).

https://github.com/llvm/llvm-project/pull/206833