RFR: 8288101: False build warning-as-error with GCC 9 after JDK-8214976

[Martin Doerr]

On Thu, 9 Jun 2022 16:35:54 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> gcc version 9.4.0 (also 9.3.1) produces build warning after [JDK-8214976](https://bugs.openjdk.org/browse/JDK-8214976):
> 
> 
> os_posix.cpp:786:34: error: call to 'exit' declared with attribute warning: use os::exit [-Werror=attribute-warning]
>   786 | ALLOW_C_FUNCTION(::exit, ::exit(num);)
>       | ~~~~~~^~~~~
> 
> 
> Apparently, GCC 9 has a bug with nesting pragmas. The [Godbolt experiments](https://godbolt.org/z/vonsqEnK6) show this only affects GCC 9, and there are no easy way to restructure the macros to dodge this, so the way out to bump the requirement for new macros to GCC >= 10.
> 
> Additional testing:
>  - [x] Linux x86_64 build with GCC 9.4.0 (now passes without warnings)
>  - [ ] Linux x86_64 build with GCC 10.2.1 (still passes)

Thanks for fixing it! LGTM.

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.org/jdk19/pull/1