RFR: 8242490: Upgrade to gcc 9.2 on Linux

Mon Apr 13 16:37:28 UTC 2020

On Mon, 13 Apr 2020 16:13:42 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> This is a compiler upgrade on Linux from the current gcc 8.3 compiler to gcc 9.2. This will match a recent upgrade done
>> for JDK 15 -- see [JDK-8241721](https://bugs.openjdk.java.net/browse/JDK-8241721).
>> On a related note, using the gcc 9 compiler produces many (harmless) warnings that will be addressed by
>> [JDK-8241476](https://bugs.openjdk.java.net/browse/JDK-8241476) -- see PR #150.
>> I have run a full build and test using this new compiler.
>
> /reviewers 2

@arapte can you also review this?

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PR: https://git.openjdk.java.net/jfx/pull/178