[jdk11u-dev] RFR: 8324598: use mem_unit when working with sysinfo memory and swap related information

[Matthias Baesken]

Backport of 8324598

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Commit messages:
 - Backport 7a798d3cebea0915f8a73af57333b3488c2091af

Changes: https://git.openjdk.org/jdk11u-dev/pull/2642/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2642&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324598
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2642.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2642/head:pull/2642

PR: https://git.openjdk.org/jdk11u-dev/pull/2642