[jdk17u-dev] RFR: 8270947: AArch64: C1: use zero_words to initialize all objects

[Goetz Lindenmaier]

I backport this for parity with 17.0.6-oracle.

I will backport the follow-ups, too.

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Commit messages:
 - Backport 6c68ce2d396c6fe02201daf2bdb8c164de807cc1

Changes: https://git.openjdk.org/jdk17u-dev/pull/792/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=792&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8270947
  Stats: 28948 lines in 8 files changed: 28783 ins; 117 del; 48 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/792.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/792/head:pull/792

PR: https://git.openjdk.org/jdk17u-dev/pull/792