RFR: 8275950: Use only _thread_in_vm in ~ThreadBlockInVMPreprocess()

[Patricio Chilano Mateo]

Please review this small change. Since _thread_in_vm is already an unsafe state there is no need to use the intermediate _thread_blocked_trans state when transitioning back in ~ThreadBlockInVMPreprocess(). Tested tiers1-3 in mach5.

Thanks,
Patricio

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Commit messages:
 - v1

Changes: https://git.openjdk.java.net/jdk/pull/6120/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6120&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275950
  Stats: 11 lines in 2 files changed: 0 ins; 9 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6120.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6120/head:pull/6120

PR: https://git.openjdk.java.net/jdk/pull/6120