RFR: JDK-8289524: Add JFR JIT restart event [v6]

[Matthias Baesken]

> The JIT compiler restarts (see restart_compiler in NMethodSweeper::sweep_code_cache) would be a helpful addition to the JFR events. Currently we log the JIT stop operations in JFR (EventCodeCacheFull) but no restart.

Matthias Baesken 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 seven additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into JDK-8289524
 - Remove JitRestart from untested events list
 - add test for JitRestart
 - Adjust test, contentType and label info
 - Bring back JitRestart event, add codeCacheMaxCapacity
 - Incorporate JIT compiler restart into EventSweepCodeCache
 - JDK-8289524

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9334/files
  - new: https://git.openjdk.org/jdk/pull/9334/files/69559d00..61d9d902

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9334&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9334&range=04-05

  Stats: 8713 lines in 253 files changed: 5494 ins; 1823 del; 1396 mod
  Patch: https://git.openjdk.org/jdk/pull/9334.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9334/head:pull/9334

PR: https://git.openjdk.org/jdk/pull/9334