[jdk21u-dev] RFR: 8341722: Fix some warnings as errors when building on Linux with toolchain clang

[Matthias Baesken]

changes to make/modules/jdk.hotspot.agent/Lib.gmk are omitted

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Commit messages:
 - Backport e7c5bf45f753ad6459c666a4dd4a31197b69e05e

Changes: https://git.openjdk.org/jdk21u-dev/pull/1167/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1167&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341722
  Stats: 10 lines in 4 files changed: 1 ins; 6 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1167.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1167/head:pull/1167

PR: https://git.openjdk.org/jdk21u-dev/pull/1167