RFR: 8306456: Don't leak _worklist's memory in PhaseLive::compute [v3]

[Johan Sjölen]

> `PhaseLive::compute` used to do this: `_worklist = new (_arena) Block_List();`. This allocates the `Block_List` to the `_arena`, but the backing array is allocated on the resource area: `Block_List() : Block_Array(Thread::current()->resource_area()), _cnt(0) {}`. This causes at most 5 worklists and at least 4 worklists to be created and not freed until the compilation is finished. This patch allocates the worklist within `PhaseLive::compute`:s local resource mark.

Johan Sjölen 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 three additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into dontleak-worklist
 - Fix style and make worklist passed in as argument
 - Don't leak the worklist in PhaseLive

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13535/files
  - new: https://git.openjdk.org/jdk/pull/13535/files/8c436ab9..81a039f5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13535&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13535&range=01-02

  Stats: 6222 lines in 152 files changed: 5434 ins; 432 del; 356 mod
  Patch: https://git.openjdk.org/jdk/pull/13535.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13535/head:pull/13535

PR: https://git.openjdk.org/jdk/pull/13535