RFR: Remove is_owning_locks() call from freeze slow path [v2]

[Patricio Chilano Mateo]

> The call to is_owning_locks() on each frame when we recurse on freeze can be removed. Instead we can check _held_monitor_count once at the beginning on freeze_internal().
> 
> Tested locally by running all tests in test/jdk/java/lang/Thread/virtual/ and jdk/jdk/internal/vm/Continuation/, and in mach5 tiers loom-tier1, loom-tier2 and loom-tier3.
> 
> Thanks,
> Patricio

Patricio Chilano Mateo has updated the pull request incrementally with one additional commit since the last revision:

  remove is_owning_locks calls from CONT_isPinned0

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

Changes:
  - all: https://git.openjdk.java.net/loom/pull/155/files
  - new: https://git.openjdk.java.net/loom/pull/155/files/8b1d052a..47e960b1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=loom&pr=155&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=loom&pr=155&range=00-01

  Stats: 38 lines in 4 files changed: 16 ins; 19 del; 3 mod
  Patch: https://git.openjdk.java.net/loom/pull/155.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/155/head:pull/155

PR: https://git.openjdk.java.net/loom/pull/155