[master] RFR: 8304341: [Lilliput] Use fixed-size lock-stack

[Roman Kennke]

Until now, we used to have a variable-sized lock-stack: when pushing an object to it and capacity is exceeded, it would re-allocate a new stack and use that. However, experiments show that the lock-stack very rarely exceeds 5 slots (I have not yet found a workload that does actually exceed it). It makes sense to make the lock-stack a fixed-size array: it makes addressing the lock-stack simpler and more efficient and it increases the likelyhood of the lock-stack being in CPU cache. If the lock-stack is ever exceeded, we would not do stack-locking at all, but instead inflate the monitor and use that.

This is already integrated in the related upstream PR: https://github.com/openjdk/jdk/pull/10907

Testing:
 - [x] tier1
 - [ ] tier2

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

Commit messages:
 - 8304341: [Lilliput] Use fixed-size lock-stack

Changes: https://git.openjdk.org/lilliput/pull/81/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput&pr=81&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304341
  Stats: 399 lines in 41 files changed: 33 ins; 263 del; 103 mod
  Patch: https://git.openjdk.org/lilliput/pull/81.diff
  Fetch: git fetch https://git.openjdk.org/lilliput pull/81/head:pull/81

PR: https://git.openjdk.org/lilliput/pull/81