[lworld] RFR: 8326860 [lworld] Illegal class modifiers in declaration of inner class

[Frederic Parain]

Fix setting of ACC_IDENTITY in old inner classes.
Clean up code fixing ACC_IDENTITY in regular classes.
Remove rejection of value enums.
This should fix all the tests failing with "java.lang.ClassFormatError: Illegal class modifiers in declaration of inner class Status (a value class) of class ..."

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Commit messages:
 - Fix ACC_IDENTITY in old inner classes and allow value enums.

Changes: https://git.openjdk.org/valhalla/pull/1047/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1047&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326860
  Stats: 22 lines in 1 file changed: 6 ins; 11 del; 5 mod
  Patch: https://git.openjdk.org/valhalla/pull/1047.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1047/head:pull/1047

PR: https://git.openjdk.org/valhalla/pull/1047