RFR: 8340012: [C2] assert(KlassEncodingMetaspaceMax > pd) failed: change encoding max if new encoding after 8338526

[Martin Doerr]

After JDK-8338526, the transformation can only be done if the Klass* is in the encoding range (also see JBS issue for more details). I've also enhanced the assertion message.

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Commit messages:
 - 8340012: [C2] assert(KlassEncodingMetaspaceMax > pd) failed: change encoding max if new encoding after 8338526

Changes: https://git.openjdk.org/jdk/pull/20971/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20971&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340012
  Stats: 6 lines in 3 files changed: 4 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20971.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20971/head:pull/20971

PR: https://git.openjdk.org/jdk/pull/20971