RFR: 8263587: C2: JVMS not cloned when needs_clone_jvms() is true

[Martin Doerr]

We need a C2 fix to prevent crashes because JVMS doesn't get cloned as needed. See linked issue for details.

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Commit messages:
 - 8263587: C2: JVMS not cloned when needs_clone_jvms() is true

Changes: https://git.openjdk.java.net/jdk/pull/3009/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3009&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263587
  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3009.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3009/head:pull/3009

PR: https://git.openjdk.java.net/jdk/pull/3009