[jdk21u-dev] RFR: 8331885: C2: meet between unloaded and speculative types is not symmetric

[Martin Doerr]

Clean backport of [JDK-8331885](https://bugs.openjdk.org/browse/JDK-8331885).

-------------

Commit messages:
 - Backport 7652f9811bfddf08650b0c3277012074873deade

Changes: https://git.openjdk.org/jdk21u-dev/pull/663/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=663&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331885
  Stats: 20 lines in 3 files changed: 12 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/663.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/663/head:pull/663

PR: https://git.openjdk.org/jdk21u-dev/pull/663