[lworld] RFR: 8292883: [lworld] javac fails to detect class files with invalid access flags

[Vicente Romero]

javac is loading a forged class file which declares a primitive class which also has the `identity` flag set. This PR is fixing this bug by issuing an error in such cases.

TIA

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Commit messages:
 - 8292883: [lworld] javac fails to detect class files with invalid access flags

Changes: https://git.openjdk.org/valhalla/pull/754/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=754&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292883
  Stats: 103 lines in 6 files changed: 102 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/754.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/754/head:pull/754

PR: https://git.openjdk.org/valhalla/pull/754