RFR: 8357473: Compilation spike leaves many CompileTasks in free list [v6]

[Aleksey Shipilev]

> See bug for more discussion.
> 
> This PR implements the "all the way" solution by removing the free list completely. It complements https://github.com/openjdk/jdk/pull/25364, and can go either first, or second. We will remerge the other one once either integrates.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `compiler`
>  - [x] Linux AArch64 server fastdebug, `all`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 11 commits:

 - Task count atomic can be relaxed
 - Minor touchup in ~CompileTask
 - Purge CompileTaskAlloc_lock completely
 - Merge branch 'master' into JDK-8357473-compile-task-free-list
 - Merge branch 'master' into JDK-8357473-compile-task-free-list
 - Merge branch 'master' into JDK-8357473-compile-task-free-list
 - Merge branch 'master' into JDK-8357473-compile-task-free-list
 - Merge branch 'master' into JDK-8357473-compile-task-free-list
 - Also free the lock!
 - Comments and indenting
 - ... and 1 more: https://git.openjdk.org/jdk/compare/7b255b8a...684f83b7

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

Changes: https://git.openjdk.org/jdk/pull/25409/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25409&range=05
  Stats: 134 lines in 6 files changed: 27 ins; 71 del; 36 mod
  Patch: https://git.openjdk.org/jdk/pull/25409.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25409/head:pull/25409

PR: https://git.openjdk.org/jdk/pull/25409