[lworld] RFR: 8309036: [lworld] Assert during C2 compilation "possible deadlock"

[Tobias Hartmann]

The fix for [JDK-8304743](https://bugs.openjdk.org/browse/JDK-8304743) that came in with the recent merge removed the `ttyUnlocker` from `ciEnv::get_klass_by_name_impl` which revealed an old regression from [JDK-8206144](https://bugs.openjdk.org/browse/JDK-8206144): A call to `ciField::layout_type()` triggers a re-computation of the type via a SystemDictionary lookup while holding the ttyLock.

Thanks,
Tobias

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

Commit messages:
 - Updated fix
 - 8309036: [lworld] Assert during C2 compilation "possible deadlock"

Changes: https://git.openjdk.org/valhalla/pull/854/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=854&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309036
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/valhalla/pull/854.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/854/head:pull/854

PR: https://git.openjdk.org/valhalla/pull/854