[jdk17] RFR: 8268676: assert(!ik->is_interface() && !ik->has_subklass()) failed: inconsistent klass hierarchy

[Vladimir Ivanov]

JDK-8267947 disabled the caching for "has_subklass() == false" and it became
more likely to observe class hierarchy changes when concurrent class loading
happens.

`ArrayCopy` optimization may observe an effectively exact klass and proceed,
but the observation can be invalidated later.

Proposed fix turns the problematic assert into a runtime check which bails out
the transformation if src input doesn't have exact klass type anymore.

Testing:
- [x] hs-tier1 - hs-tier2

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk17/pull/67/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=67&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268676
  Stats: 8 lines in 1 file changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/67.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/67/head:pull/67

PR: https://git.openjdk.java.net/jdk17/pull/67