RFR: JDK-8318089: Class space not marked as such with NMT when CDS is off

[Thomas Stuefe]

If Xshare is off, we don't correctly register class space with NMT. We should do that.

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Commit messages:
 - JDK-8318089-Class-space-not-marked-as-such-with-NMT-when-CDS-is-off

Changes: https://git.openjdk.org/jdk/pull/16184/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16184&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318089
  Stats: 9 lines in 1 file changed: 3 ins; 6 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16184.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16184/head:pull/16184

PR: https://git.openjdk.org/jdk/pull/16184