RFR: 8314165: [lw5] check for illegal circularity at class loading time [v2]

[Vicente Romero]

> This PR is implementing this assertion of JEP 401:
> 
> 
> At class load time, an error occurs if an ACC_DEFAULT class has an illegal circularity in its instance field types
> 
> 
> which is in section: `class file representation & interpretation`
> 
> So for example if a Java compiler were able to create a class file for class:
> 
> value class Test {
>     Test! test; // illegal circularity
>     public implicit Test();
> }
> 
> then javac should issue an error while loading such a class

Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:

  more fine tunning

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/903/files
  - new: https://git.openjdk.org/valhalla/pull/903/files/c957eb63..a36a42ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=903&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=903&range=00-01

  Stats: 9 lines in 2 files changed: 7 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/903.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/903/head:pull/903

PR: https://git.openjdk.org/valhalla/pull/903