[clang] [clang][test] Rewrote test to work with lit internal shell syntax (PR #105902)

[Paul Kirth via cfe-commits]

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+import argparse
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ilovepi wrote:

does this require a license/copyright header?  

I see a `#!/usr/bin/env python` in https://github.com/llvm/llvm-project/blob/cdd11d694a406a98a16d6265168ee2fbe1b6a87c/llvm/utils/lit/tests/Inputs/shtest-env/print_environment.py#L1, do yo need something similar here? You're using python to invoke, so it's probably fine, but it seems a bit inconsistent. Do you know what's more typical in the test support scripts like this?

https://github.com/llvm/llvm-project/pull/105902