RFR: JDK-8247589: Implementation of Alpine Linux/x64 Port

[Aleksei Voitylov]

continuing the review thread from here https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-September/068546.html

> The download side of using JNI in these tests is that it complicates the
> setup a bit for those that run jtreg directly and/or just build the JDK
> and not the test libraries. You could reduce this burden a bit by
> limiting the load library/isMusl check to Linux only, meaning isMusl
> would not be called on other platforms.
>
> The alternative you suggest above might indeed be better. I assume you
> don't mean splitting the tests but rather just adding a second @test
> description so that the vm.musl case runs the test with a system
> property that allows the test know the expected load library path behavior.

I have updated the PR to split the two tests in multiple @test s.

> The updated comment in java_md.c in this looks good. A minor comment on
> Platform.isBusybox is Files.isSymbolicLink returning true implies that
> the link exists so no need to check for exists too. Also the
> if-then-else style for the new class in ProcessBuilder/Basic.java is
> inconsistent with the rest of the test so it stands out.

Thank you, these changes are done in the updated PR.

> Given the repo transition this weekend then I assume you'll create a PR
> for the final review at least. Also I see JEP 386 hasn't been targeted
> yet but I assume Boris, as owner, will propose-to-target and wait for it
> to be targeted before it is integrated.

Yes. How can this be best accomplished with the new git workflow?
- we can continue the review process till the end and I will request the integration to happen only after the JEP is
  targeted. I guess this step is now done by typing "slash integrate" in a comment.
- we can pause the review process now until the JEP is targeted.

In the first case I'm kindly asking the Reviewers who already chimed in on that to re-confirm the review here.

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Commit messages:
 - JDK-8247589: Implementation of Alpine Linux/x64 Port

Changes: https://git.openjdk.java.net/jdk/pull/49/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=49&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8247589
  Stats: 403 lines in 30 files changed: 346 ins; 17 del; 40 mod
  Patch: https://git.openjdk.java.net/jdk/pull/49.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/49/head:pull/49

PR: https://git.openjdk.java.net/jdk/pull/49