RFR: 8365400: Enhance JFR to emit file and module metadata for class loading

[Markus Grönlund]

Greetings,

this enhancement adds a "source" field, label "Location" to the jdk.ClassDefine event.

To enable this functionality, JFR needs a concurrent symbol table. We can build a simpler version of a concurrent hash table, taking advantage of the JFR epoch system. This will be useful also for planned future enhancements.

Extensions are made to AOT to consistently report identical canonical paths for classes as non-AOT code paths.

Testing: jdk_jfr, manual AOT verification, stress testing

Thanks
Markus

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

Commit messages:
 - symboltable_and_location

Changes: https://git.openjdk.org/jdk/pull/28505/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28505&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365400
  Stats: 1360 lines in 34 files changed: 1034 ins; 162 del; 164 mod
  Patch: https://git.openjdk.org/jdk/pull/28505.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28505/head:pull/28505

PR: https://git.openjdk.org/jdk/pull/28505