Make ‘cabal exec’ not pass -package-env to called executable

[sergv]

Summary

The cabal exec always passed only the options user explicitly specified but after #10828 started passing -package-env as well.

This is a followup to #10828 that fixes cabal exec that passes -package-env flag to all executables if underlying ghc supports env files. This breaks said executables.

Longer version

cabal exec started passing -package-env=- to all executables if
underlying GHC supports env files. This makes the called executable
fail if it doesn’t support the -package-env flag, which many
executables don’t.

This change restores old cabal exec behaviour to call regular
executables without any extra command-line options and keeps fixes in
PR 10828 that passes -package-env when dealing with GHC in other
cabal commands. GHC is not typically called via cabal exec but the
PR 10828 made other commands like cabal build pass the flag. This PR
attempts to maintain that.

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[ulysses4ever]

Sounds good to me but it'd be great to have the author of #10828 weigh in, @mpickering

[mpickering]

Looks good to me, thanks for the precise fix.

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ❌ Validate post job

You can check the last failing draft PR here: #11009.

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[mergify]

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