[lworld] RFR: 8249869: [lworld] Remove LW2 specific code from the JIT [v3]

[Tobias Hartmann]

> The concept of flattenable fields needs some cleanup (inline types are always flattenable/null-free). We can remove the
> side-channel introduced by JDK-8212190. See JDK-8247357 for details.

Tobias Hartmann has updated the pull request with a new target base due to a merge or a rebase. The pull request now
contains three commits:

 - Merge lworld
 - Minor follow-up fix to handle unloaded inline klasses in C1 and correct casting of OSR inline args in C2
 - 8249869: [lworld] Remove LW2 specific code from the JIT

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Changes: https://git.openjdk.java.net/valhalla/pull/116/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/116/webrev.02
  Stats: 363 lines in 37 files changed: 16 ins; 193 del; 154 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/116.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/116/head:pull/116

PR: https://git.openjdk.java.net/valhalla/pull/116