[jdk11u-dev] RFR: 8247591: Document Alpine Linux build steps in OpenJDK build guide

[Aleksei Voitylov]

JDK-8247591 is in the docs issue in the third batch of a chain of backports for Alpine support to 11u as discussed in the mailing list. For the full set of anticipated changes please refer to the jdk-updates mailing list [1].

Original changeset does not apply cleanly because of:

8220164: Fix build instructions for AIX
8244224: Implementation of JEP 381: Remove the Solaris and SPARC Ports

Testing: JCK + JTreg on Windows, Linux, Solaris, Mac without regressions.

[1] https://mail.openjdk.java.net/pipermail/jdk-updates-dev/2022-February/012271.html

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Commit messages:
 - JDK-8247591 backport to 11u

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/911/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=911&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8247591
  Stats: 51 lines in 2 files changed: 51 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/911.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/911/head:pull/911

PR: https://git.openjdk.java.net/jdk11u-dev/pull/911