RFR: 8233380: CHT: Node allocation and freeing

[Ivan Walulya]

Hi all,

Please review this change to pass an allocator ("context") instance to the CHT at initialization instead of relying on the static configuration. The allocator instance is passed down to the allocate/free_node methods making it easier to use Arena-style allocators in the CHT.

Testing: tier1-3

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Commit messages:
 - add allocator context and modify tests to match the changes

Changes: https://git.openjdk.java.net/jdk/pull/4081/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4081&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233380
  Stats: 75 lines in 7 files changed: 23 ins; 7 del; 45 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4081.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4081/head:pull/4081

PR: https://git.openjdk.java.net/jdk/pull/4081