RFR: Remove is_owning_locks() call from freeze slow path

[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

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

Commit messages:
 - v1

Changes: https://git.openjdk.java.net/loom/pull/155/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=155&range=00
  Stats: 36 lines in 1 file changed: 8 ins; 23 del; 5 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