RFR: JDK-8323008: filter out harmful -std* flags added by autoconf from CXX [v4]

[Magnus Ihse Bursie]

On Thu, 11 Jan 2024 14:31:47 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> It was observed, that autoconf 2.72 added on macOS x86_64 the flag -std=gnu++11 by default to CXX in the configure process .
>> This is not really wanted so better remove / filter out those -std* flags added by autoconf from CXX .
>> 
>> Seems we have something similar for some time for CFLAGS and CXXFLAGS ( see TOOLCHAIN_POST_DETECTION in make/autoconf/toolchain.m4) that
>>  dates back to JDK 9.
>> 
>> See the discussion about this issue : https://mail.openjdk.org/pipermail/build-dev/2024-January/042551.html
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust GREP, remove unneeded test

The grep fixes are excellent, thank you for those! 

The CXX filtering is a hack, and I'm slightly less happy about that. Otoh, the entire autoconf compiler detection stuff is so-so, and we're basically trying to avoid getting entangled in it, so I guess adding yet another workaround is okay.

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Marked as reviewed by ihse (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17301#pullrequestreview-1817994834