[jdk17u-dev] RFR: 8296437: NMT incurs costs if disabled

[Goetz Lindenmaier]

A small improvement of memory. Nice to have.

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Commit messages:
 - Backport 9f8b6d2aa6733efb69d2d4f7e5f9e09dc5df9800

Changes: https://git.openjdk.org/jdk17u-dev/pull/1808/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1808&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296437
  Stats: 30 lines in 3 files changed: 27 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1808.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1808/head:pull/1808

PR: https://git.openjdk.org/jdk17u-dev/pull/1808