RFR: 8271898: disable os.release_multi_mappings_vm on macOS-X64

[Daniel D.Daugherty]

A trivial fix to disable os.release_multi_mappings_vm on macOS-X64.

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Commit messages:
 - 8271898: disable os.release_multi_mappings_vm on macOS-X64

Changes: https://git.openjdk.java.net/jdk/pull/5006/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5006&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271898
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5006.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5006/head:pull/5006

PR: https://git.openjdk.java.net/jdk/pull/5006