RFR: 8292916: Streamline LoaderConstraint purging [v2]

[Coleen Phillimore]

> The code to purge loader constraints walks through the class loader list of an unloaded class, and then asserts that the there are no leftovers. It can just directly remove the list of loaders without that walk.
> 
> Also I left the variable name 'probe' to help with diffs for [JDK-8291969](https://bugs.openjdk.org/browse/JDK-8291969) a little, but it's a bad variable name.
> 
> Tested with tier1-3 which contains jck tests.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Unrename probe to constraint

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10023/files
  - new: https://git.openjdk.org/jdk/pull/10023/files/dae25c41..d9726237

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10023&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10023&range=00-01

  Stats: 13 lines in 1 file changed: 0 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/10023.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10023/head:pull/10023

PR: https://git.openjdk.org/jdk/pull/10023