RFR: Inject jvmti state into Thread.

[Coleen Phillimore]

The jvmtiThreadState field should be injected into Thread and not visible to Java code.

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Commit messages:
 - Inject jvmti state into Thread.

Changes: https://git.openjdk.java.net/loom/pull/54/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=54&range=00
  Stats: 11 lines in 4 files changed: 7 ins; 4 del; 0 mod
  Patch: https://git.openjdk.java.net/loom/pull/54.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/54/head:pull/54

PR: https://git.openjdk.java.net/loom/pull/54