RFR: 8252191: Update to gcc 10.2 on Linux

[Kevin Rushforth]

On Tue, 6 Oct 2020 10:47:47 GMT, Johan Vos <jvos at openjdk.org> wrote:

>> Build and sanity test looks good on my machine.
>
>> Build and sanity test looks good on my machine.
> 
> What OS are you using? (I'm running a test on Ubuntu 18.04)

I've run tests on Ubuntu 16.04, Ubuntu 20.04, and Oracle Linux 7.

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PR: https://git.openjdk.java.net/jfx/pull/311