RFR: 8256535: C2: randomize CCP processing order for stress testing

[Roberto Castañeda Lozano]

On Mon, 14 Dec 2020 12:42:49 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Add 'StressCCP' option to randomize the selection of the node to be examined in
>> each CCP iteration.
>
> Tested with:
> 
> -  test cases updated in this change (`TestStressOptions.java`, `TestGenerateStressSeed.java`, `TestStressIGVNAndCCP.java`)
> - 20 repetitions of the `hotspot_compiler` test group with `-XX:+StressCCP`

I assume the failures in the GitHub pre-submit tests are due to some problem with the GitHub Actions setup, as the same tests pass locally.

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PR: https://git.openjdk.java.net/jdk/pull/1765