RFR: 8262454: Handshake timeout improvements, single target, kill unfinished thread [v5]

[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.

Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:

  Sorted imports

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2743/files
  - new: https://git.openjdk.java.net/jdk/pull/2743/files/e6585f93..19165205

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2743&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2743&range=03-04

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 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