RFR: 8262454: Handshake timeout improvements, single target, kill unfinished thread

[Robbin Ehn]

When executing a single target handshake we do not have a timeout.
When we timeout we should crash the thread with the non-completed handshake operation.

VM_Handshake only had one implementer so I remove it.

Passes t1-5.

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Commit messages:
 - Fixed timeout

Changes: https://git.openjdk.java.net/jdk/pull/2743/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2743&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262454
  Stats: 152 lines in 3 files changed: 122 ins; 9 del; 21 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2743.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2743/head:pull/2743

PR: https://git.openjdk.java.net/jdk/pull/2743