RFR: JDK-8298035: Provide better descriptions for JIT compiler JFR events [v3]

[Matthias Baesken]

> Most Compiler related JFR events lack descriptions, see
> https://sap.github.io/SapMachine/jfrevents/20.html#jvm-compiler
> 
> We should add some helpful description texts for these JFR events.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  Change some descriptions

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11506/files
  - new: https://git.openjdk.org/jdk/pull/11506/files/46f5aa65..03afa379

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11506&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11506&range=01-02

  Stats: 8 lines in 1 file changed: 0 ins; 4 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/11506.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11506/head:pull/11506

PR: https://git.openjdk.org/jdk/pull/11506