[jdk21u-dev] RFR: 8308286: Fix clang warnings in linux code

[Varada M]

Building JDK 21 with clang 16 on linux was successful along with changes from [pull/874](https://github.com/openjdk/jdk21u-dev/pull/874). Tier1 testing was successful with release debug level.

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Commit messages:
 - Backport 98a954eebc4f97dd16cb89bd4f1122952c8482ca

Changes: https://git.openjdk.org/jdk21u-dev/pull/875/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=875&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308286
  Stats: 20 lines in 6 files changed: 14 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/875.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/875/head:pull/875

PR: https://git.openjdk.org/jdk21u-dev/pull/875