RFR: 8351655: Optimize ObjectMonitor::unlink_after_acquire() [v2]

[Fredrik Bredberg]

> This PR implements an optimization of `ObjectMonitor::unlink_after_acquire()`. If it's possible it only converts the first part (the singly linked part) of the `entry_list` into a doubly linked list and leave the _entry_list_tail pointer untouched. 
> 
> It has passed tier1-tier8 tests.

Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:

  Update after review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24078/files
  - new: https://git.openjdk.org/jdk/pull/24078/files/12581560..e6d1ed81

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24078&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24078&range=00-01

  Stats: 17 lines in 1 file changed: 4 ins; 2 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/24078.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24078/head:pull/24078

PR: https://git.openjdk.org/jdk/pull/24078