[jdk11u-dev] RFR: 8209380: ARM: cleanup maybe-uninitialized and reorder compiler warnings

[Christoph Langer]

Please review the backport of JDK-8209380. It is another prereq to get the upcoming GitHub Actions workflow green. The patch applies cleanly and follow up JDK-8209193 is already in 11u.
If it weren't integrated, the GHA crossbuild of hotspot for arm would fail.

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Depends on: https://git.openjdk.java.net/jdk11u-dev/pull/185

Commit messages:
 - 8209380: ARM: cleanup maybe-uninitialized and reorder compiler warnings

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/186/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=186&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8209380
  Stats: 9 lines in 4 files changed: 5 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/186.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/186/head:pull/186

PR: https://git.openjdk.java.net/jdk11u-dev/pull/186