RFR: 8256393: Github Actions build on Linux should define OS and GCC versions

[Magnus Ihse Bursie]

On Mon, 16 Nov 2020 14:27:39 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> We should be more explicit about OS and compiler versions used in the GitHub Actions builds, to avoid problems caused by unexpected changes to the defaults. This patch changes the OS and GCC versions used from ubuntu-latest (currently 18.04, but will change to 20.04 sometime soon) / default (currently 9.3.0) to 20.04 / 10.2.0.
>
> .github/workflows/submit.yml line 190:
> 
>> 188:         run: |
>> 189:           sudo apt-get install libxrandr-dev libxtst-dev libcups2-dev libasound2-dev
>> 190:           sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 100 --slave /usr/bin/g++ g++ /usr/bin/g++-10
> 
> Maybe we should use apt-get functionality to install a specific version of packages? I'm not sure how relevant it is for the X and alsa libraries since they change very seldom, but perhaps for gcc, to get a specific point release of the compiler.

Something along the lines of `sudo apt-get install gcc-10=10.2.0-5ubuntu1~20`, which I believe should match quite well the version used internally in the Oracle CI builds.

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PR: https://git.openjdk.java.net/jdk/pull/1225