RFR: 8265602: -XX:DumpLoadedClassList should support custom loaders [v3]

[Ioi Lam]

> Some applications load a lot of classes using custom loaders. This PR improves the start-up performance of these apps when using a "static" CDS archive:
> 
> Here are performance numbers for the Eclipse IDE:
> 
> 
> Static Archive Before: 7.31 sec (classlist does not include custom loader classes)
> Static Archive After:  6.49 sec (classlist includes custom loader classes)
> Dynamic Archive:       6.62 sec

Ioi Lam 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 three additional commits since the last revision:

 - Merge branch 'master' into 8265602-dump-loaded-class-list-custom-loader
 - @calvinccheung comments
 - 8265602: -XX:DumpLoadedClassList should support custom loaders

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4952/files
  - new: https://git.openjdk.java.net/jdk/pull/4952/files/04ae4859..c7764978

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4952&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4952&range=01-02

  Stats: 5987 lines in 283 files changed: 3970 ins; 1177 del; 840 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4952.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4952/head:pull/4952

PR: https://git.openjdk.java.net/jdk/pull/4952