[jdk18] RFR: 8275638: GraphKit::combine_exception_states fails with "matching stack sizes" assert

[Roland Westrelin]

The bug and fix were discussed in a previous PR:

https://github.com/openjdk/jdk/pull/6572

I pushed all commits from that PR on top of jdk 18 and added a couple
extra tests as suggested in:

https://github.com/openjdk/jdk/pull/6572#issuecomment-994086590

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Commit messages:
 - whitespaces
 - extra tests
 - comment
 - alternate fix
 - make test runnable with release build
 - more
 - fix

Changes: https://git.openjdk.java.net/jdk18/pull/29/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=29&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275638
  Stats: 117 lines in 3 files changed: 117 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/29.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/29/head:pull/29

PR: https://git.openjdk.java.net/jdk18/pull/29