[llvm] [llvm-lit] Print environment variables when using env without subcommand (PR #98414)

[James Henderson via llvm-commits]

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@@ -1,3 +1,5 @@
+## Tests the env command's ability to handle setting, unsetting, and mixing environment variables.
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jh7370 wrote:

I think probably `env-no-subcommand.txt` would be the name that best-conveys its meaning. It looks like the common factor in these tests is that no additional process exists that is run with the env-specified variables.

https://github.com/llvm/llvm-project/pull/98414