RFR: 8338939: Simplify processing of hidden class names [v2]

[Markus Grönlund]

> Greetings,
> 
> The name symbol for hidden (anonymous) classes has evolved. Initially, it consisted of only a base class name, e.g., "java/lang/invoke/LambdaForm$BMH", so JFR had to introduce a scheme for disambiguating one anonymous class from another.
> 
> The scheme (which still exists in JFR) appends the Java class mirror's hashcode to the base class name, e.g., "java/lang/invoke/LambdaForm$BMH/22626602".
> 
> With [JDK-8238358](https://bugs.openjdk.org/browse/JDK-8238358), the disambiguation of hidden class names is now intrinsic to the processing by the ClassFileParser. This is done by appending the InstanceKlass address to the base class name, e.g., "java/lang/invoke/LambdaForm$BMH+0x000000001d190000".
> 
> An argument can be made that JFR specialization for hidden (anonymous) classes may no longer be necessary. Indeed, the result now involves a "double" disambiguation: e.g., "java/lang/invoke/LambdaForm$BMH+0x000000001d190000/231202600".
> 
> It is now possible to simplify the handling of hidden (anonymous) class names, which avoids using the Java mirror oop. We might want to keep the "/" construct as that might be an implicit invariant on users' expectations (quickly done by replacing "+" with "/").
> 
> Testing: jdk_jfr
> 
> Thanks
> Markus

Markus Grönlund has updated the pull request incrementally with two additional commits since the last revision:

 - cleanup
 - use existing k->external_name

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20708/files
  - new: https://git.openjdk.org/jdk/pull/20708/files/805d78d5..cb10d174

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20708&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20708&range=00-01

  Stats: 25 lines in 1 file changed: 0 ins; 23 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20708.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20708/head:pull/20708

PR: https://git.openjdk.org/jdk/pull/20708