[lworld] Integrated: 8376890: [lworld] Compiler replay crashes when class cannot be loaded after JDK-8375548

[Christian Hagedorn]

[JDK-8375548](https://bugs.openjdk.org/browse/JDK-8375548) added support for compiler replay but only tested with cases where classes can actually be loaded. When some classes cannot be loaded (for example, due to missing class files), we crash with a null pointer when run with `+ReplayIgnoreInitErrors`: `parse_klass()` returns `null` for non-loadable classes. Then, we access it with `k->is_objArray_klass()` without checking for null and we crash. This patch adds a simple null-check to fix the problem.

Thanks,
Christian

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Commit messages:
 - 8376890: [lworld] Compiler replay crashes when class cannot be loaded after JDK-8375548

Changes: https://git.openjdk.org/valhalla/pull/2010/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2010&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376890
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/2010.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2010/head:pull/2010

PR: https://git.openjdk.org/valhalla/pull/2010