[jdk21u-dev] RFR: 8345569: [ubsan] adjustments to filemap.cpp and virtualspace.cpp for macOS aarch64

[Matthias Baesken]

8345569: [ubsan] adjustments to filemap.cpp and virtualspace.cpp for macOS aarch64

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Commit messages:
 - Backport 1d2ccaeaa316029772b5de3dc5579ee7b1363b60

Changes: https://git.openjdk.org/jdk21u-dev/pull/1397/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1397&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345569
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1397.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1397/head:pull/1397

PR: https://git.openjdk.org/jdk21u-dev/pull/1397