RFR: 8253750: use build-stable default seed for Utils.RANDOM_GENERATOR [v3]

[Roger Riggs]

On Mon, 5 Oct 2020 21:27:00 GMT, Igor Ignatyev <iignatyev at openjdk.org> wrote:

>> Can you take a look at the existing jdk.test.lib.RandomFactory and see if we can avoid a separate random number
>> generator and property?
>
>> Can you take a look at the existing jdk.test.lib.RandomFactory and see if we can avoid a separate random number
>> generator and property?
> 
> I am not adding a new separate random number generator or a new property, `jdk.test.lib.Utils.getRandomInstance` has
> been around for a long time and is used by lots of tests (most of them are in `/test/hotspot/jtreg`). merging
> `Utils.getRandomInstance` and `RandomFactory` (or rather replacing one w/ another) is tracked by
> [JDK-8212077](https://bugs.openjdk.java.net/browse/JDK-8212077).

I was thinking that the code added to Utils.SEED initialization could just have easily been added to
RandomFactory.getSystemSeed() and not have to be changed later.

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PR: https://git.openjdk.java.net/jdk/pull/391