RFR: 8257803: Add -Xbatch to compiler/blackhole tests

[David Holmes]

On Sun, 6 Dec 2020 23:10:22 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Newly added tests miss `-Xbatch`, which makes them sensitive to compilation delays, especially when running in parallel with many other tests. There are already failures observed in current testing. While there might be other causes, this patch eliminates the most obvious one.
> 
> The run time of the tests are not affected, because the tests are still small.
> 
> Testing:
>  - [x] `compiler/blackhole` tests running in larger `hotspot:tier1` suite (added separately, 5 of 5 runs pass)

Previously failing tests now seem to be passing in our CI.

Thanks,
David

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1653