RFR: 7903164: cleanup jextract options [v2]

[Maurizio Cimadamore]

On Fri, 15 Apr 2022 11:46:46 GMT, Athijegannathan Sundararajan <sundar at openjdk.org> wrote:

>> * added -D option for preprocessor macros
>> * renamed -d as --output
>> * added support for ./compile_flags.txt to pass extra clang options to jextract
>> * removed -C option
>
> Athijegannathan Sundararajan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   argValue check for starting with '-' was in wrong place.

Looks good - added a comment on the md file

README.md line 134:

> 132: 
> 133: If you want to pass extra options to clang compiler, you can create a file named _compile_flags.txt_ in the current directory.
> 134: That text file can contain clang compiler options one per each line.

Suggestion:

#### Additional clang options

Users can specify additional clang compiler options, by creating a file named `compile_flags.txt` in the current folder, as described [here](https://clang.llvm.org/docs/JSONCompilationDatabase.html#alternatives).

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.java.net/jextract/pull/23