RFR: 8301341: LinkedTransferQueue does not respect timeout for poll() [v5]

[Doug Lea]

> This now uses Thread.isVirtual to distinguish spin vs immediate block cases, enabling re-introduction of spin control from the previous version, removing anomalies like this one.

Doug Lea has updated the pull request incrementally with one additional commit since the last revision:

  Fix inverted test assert; improve internal documentation; simplify code

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14317/files
  - new: https://git.openjdk.org/jdk/pull/14317/files/71b9c8bf..2f591a0b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14317&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14317&range=03-04

  Stats: 144 lines in 3 files changed: 46 ins; 44 del; 54 mod
  Patch: https://git.openjdk.org/jdk/pull/14317.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14317/head:pull/14317

PR: https://git.openjdk.org/jdk/pull/14317