RFR: 8369219: JNI::RegisterNatives causes a memory leak in CodeCache [v6]

[Francesco Andreuzzi]

> I propose to amend `nmethod::is_cold` to let GC collect not-entrant native `nmethod` instances.
> 
> Passes tier1 and tier2 (fastdebug).

Francesco Andreuzzi 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 15 additional commits since the last revision:

 - cc
 - Merge branch 'master' into JDK-8369219
 - nn
 - update foundOne
 - fix summary
 - nn
 - Merge branch 'master' into JDK-8369219
 - trigger
 - nn
 - othervm
 - ... and 5 more: https://git.openjdk.org/jdk/compare/61d601ae...b6d94cf8

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27742/files
  - new: https://git.openjdk.org/jdk/pull/27742/files/98754ee8..b6d94cf8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27742&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27742&range=04-05

  Stats: 32964 lines in 799 files changed: 19857 ins; 8954 del; 4153 mod
  Patch: https://git.openjdk.org/jdk/pull/27742.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27742/head:pull/27742

PR: https://git.openjdk.org/jdk/pull/27742