RFR: 8238650: Allow to override buildDate with SOURCE_DATE_EPOCH

[Bernhard M.Wiedemann]

On Fri, 7 Feb 2020 13:43:50 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> So the contributor agreement is done. How can I find the bug?
> 
> The OCA needs to be validated and recorded. As for the bug, it has been transferred to the JDK project as [JDK-8238650](https://bugs.openjdk.java.net/browse/JDK-8238650).

> The OCA needs to be validated and recorded.

https://www.oracle.com/technetwork/community/oca-486395.html#w now has
`Bernhard Wiedemann - OpenJDK - bmwiedemann`

> As for the bug, it has been transferred to the JDK project as [JDK-8238650](https://bugs.openjdk.java.net/browse/JDK-8238650).

Thanks, somehow I had not got an email notification for that.
Also worth noting that this PR only fixes one of the sources of non-determinism in openjfx. Do I have to open a separate bug for each of them?

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

PR: https://git.openjdk.java.net/jfx/pull/99