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

[James Henderson via llvm-commits]

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@@ -1,32 +1,32 @@
-# Check default environment.
+## Check default environment.
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jh7370 wrote:

Thanks for improving the comments in this test, but the other test files modified/added in this PR need the same treatment.

While you're at it, could you add a comment at the very top of the file, separated with a blank line from first test case's comment, that explains the general purpose of the tests in this file, please. (Same goes for the other ones too).

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