Integrated: Strip out TWR scope locals

[Andrew Haley]

Remove try-with-resources ScopeLocal bindings.

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Commit messages:
 - Use ThreadLocalRandom to choose victim.
 - Remove TwR-style bindings.
 - Merge https://github.com/openjdk/loom into fibers
 - Merge https://github.com/openjdk/loom into fibers
 - Merge https://github.com/openjdk/loom into fibers
 - Merge https://github.com/openjdk/loom into fibers
 - Merge https://github.com/openjdk/loom into fibers
 - Merge https://github.com/openjdk/loom into fibers
 - Merge branch 'fibers' of https://github.com/openjdk/loom into fibers
 - Merge branch 'fibers' of https://github.com/openjdk/loom into fibers
 - ... and 16 more: https://git.openjdk.java.net/loom/compare/fa33ae75...47f650a0

Changes: https://git.openjdk.java.net/loom/pull/89/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=89&range=00
  Stats: 417 lines in 8 files changed: 44 ins; 366 del; 7 mod
  Patch: https://git.openjdk.java.net/loom/pull/89.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/89/head:pull/89

PR: https://git.openjdk.java.net/loom/pull/89