RFR: Fix tests

[Andrew Haley]

Integrate latest version of scope locals.

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Commit messages:
 - Fix tests
 - Make scope locals a preview feature
 - Fix include
 - Fix merge
 - Suggested changes
 - Clear scope-local bindings on ThreadDeath.
 - Clear scope local bindings on realloc_failures during deoptimization.
 - Cleanup, add Javadoc.
 - Temeporary commit for branch
 - Use immutable memory for pointer to ScopeLocal cache
 - ... and 18 more: https://git.openjdk.java.net/loom/compare/109284fd...db102a73

Changes: https://git.openjdk.java.net/loom/pull/39/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=39&range=00
  Stats: 538 lines in 13 files changed: 313 ins; 65 del; 160 mod
  Patch: https://git.openjdk.java.net/loom/pull/39.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/39/head:pull/39

PR: https://git.openjdk.java.net/loom/pull/39