RFR: 8351851: Update PmemTest to run on AMD64

[Ivan Šipka]

review to facilitate visibility on changes prior to testing @bwhuang-us

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Commit messages:
 - trailing whitespace fix
 - trailing whitespace fix
 - all OS architectures are treated equally

Changes: https://git.openjdk.org/jdk/pull/24416/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24416&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351851
  Stats: 21 lines in 1 file changed: 6 ins; 12 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/24416.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24416/head:pull/24416

PR: https://git.openjdk.org/jdk/pull/24416