RFR: 7903156: remove jopt-simple dependency from jextract [v5]

[Maurizio Cimadamore]

On Wed, 13 Apr 2022 03:32:23 GMT, Athijegannathan Sundararajan <sundar at openjdk.org> wrote:

>> removed jopt-simple dependency as well as moditect grade plugin dependency. Piggybacking build.gradle change to enforce 'jtreg_home' check in jtreg task's doFirst block.
>
> Athijegannathan Sundararajan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   accidentally moved CommandLine.java to a different dir. Fixed -C "-D Foo" handling.
>   cleaned code and commented.

Looks good - all the single option business (which we inherited from jopt) looks shady and fragile, so we should probably try to simplify at some point by abandoning the concept of supporting `-lclang` and require `--with-lib clang` instead (as I find the analogy with the C compiler option quite weak anyway). The problematic option to parse is -C, and I wonder if perhaps we could simplify by delegating to an environment variable.

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.java.net/jextract/pull/19