RFR: 8355915: [leyden] Crash in MDO clearing the unloaded array type [v3]

[Aleksey Shipilev]

> Caught this when doing benchmarks with Spring Boot. See the bug for reproducer.
> 
> The lifecycle of array types of `T` is bound to the lifecycle of `T` themselves. So the fix does similar thing to `is_excluded` and other code: when we encounter the `T[]`, we ask if its bottom component classes is not yet initialized. This fits nicely with our current uses, which skip such classes, and ever touch their (potentially nullptr) CLDs.
> 
> Additional testing:
>  - [x] Ad-hoc testing with most recent spring-boot-petclinic
>  - [x] Linux x86_64 server fastdebug, `runtime/cds`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Co-opt Igor's fix
 - Merge branch 'premain' into JDK-8355915-mdo-array-crash
 - More robust fix
 - Fix
 - Fix

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

Changes:
  - all: https://git.openjdk.org/leyden/pull/64/files
  - new: https://git.openjdk.org/leyden/pull/64/files/5808fd73..13f6b163

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=64&range=02
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=64&range=01-02

  Stats: 220 lines in 14 files changed: 168 ins; 28 del; 24 mod
  Patch: https://git.openjdk.org/leyden/pull/64.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/64/head:pull/64

PR: https://git.openjdk.org/leyden/pull/64