[jdk21u-dev] RFR: 8321931: memory_swap_current_in_bytes reports 0 as "unlimited"

[Goetz Lindenmaier]

I backport this for parity with 21.0.8-oracle

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Commit messages:
 - Backport 7777eb5e15b9f08cdc621c84ff38c72334388b56

Changes: https://git.openjdk.org/jdk21u-dev/pull/1567/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1567&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321931
  Stats: 98 lines in 2 files changed: 97 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1567.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1567/head:pull/1567

PR: https://git.openjdk.org/jdk21u-dev/pull/1567