RFR: 8254263: Remove special_runtime_exit_condition() check from ~ThreadInVMForHandshake()

[Patricio Chilano Mateo]

Hi all,

Please review the following patch that removes the call to handle_special_runtime_exit_condition() in
~ThreadInVMForHandshake(). This check was added by 8223572 to prevent a JavaThread that was suspended while trying to
process a handshake to transition back to java without noticing it was suspended. Since 8238761, a JavaThread executing
HandshakeState::process_by_self() will never become safe. It comes from an unsafe state and remains unsafe, so it
cannot be suspended during that time. Removing this check also removes one of the reasons
SafepointMechanism::process_if_requested() is recursive (the other one remains SafepointSynchronize::block()). Tested
in mach5, tiers 1-7.

Thanks,
Patricio

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Commit messages:
 - v1

Changes: https://git.openjdk.java.net/jdk/pull/577/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=577&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254263
  Stats: 28 lines in 3 files changed: 5 ins; 20 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/577.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/577/head:pull/577

PR: https://git.openjdk.java.net/jdk/pull/577