[jdk21u] RFR: 8312591: GCC 6 build failure after JDK-8280982

[Aleksey Shipilev]

On Wed, 2 Aug 2023 08:22:52 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Clean backport to upgrade older toolchains.
> Risk is low, adds a few warning exclusions.
> 
> Additional testing:
>  - [x] GHA

GHA is not clean due to unrelated infra reasons. Push approval is here.

-------------

PR Comment: https://git.openjdk.org/jdk21u/pull/32#issuecomment-1664204790