RFR: 8241390: 'Deadlock' with VM_RedefineClasses::lock_classes()

[Daniil Titov]

The change fixes a 'deadlock' situation in VM_RedefineClasses::lock_classes() when the current thread is in the middle
of redefining the same class. The change is based on the fix [1] suggested in the Jira issue [2] comment.

[1] http://cr.openjdk.java.net/~jiangli/8241390/webrev.00/
[2] https://bugs.openjdk.java.net/browse/JDK-8241390

Testing: :jdk_instrument, tier1-tier3, and tier5 tests pass.

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Commit messages:
 - 8241390: 'Deadlock' with VM_RedefineClasses::lock_classes()

Changes: https://git.openjdk.java.net/jdk/pull/190/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=190&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8241390
  Stats: 202 lines in 6 files changed: 193 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/190.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/190/head:pull/190

PR: https://git.openjdk.java.net/jdk/pull/190