RFR: 8267446: Taskqueue code fails with assert(bottom_relaxed() == age_top_relaxed()) failed: not empty

[Kim Barrett]

Please review this change to TaskTerminator to no longer verify the queues
are empty in its destructor. The terminator's destructor may be called after
the queues have been deleted, as happens in ~ZHeapIterator().

There is no loss of error checking by this change.  The TaskTerminator
already verifies the queues are empty on normal termination.

Testing:
mach5 tier1, hs-tier6-gc (the latter being where the failure showed up).
The failure seems to be very intermittent; I've not been able to reproduce it.

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

Commit messages:
 - remove assertion

Changes: https://git.openjdk.java.net/jdk/pull/4156/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4156&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267446
  Stats: 3 lines in 2 files changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4156.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4156/head:pull/4156

PR: https://git.openjdk.java.net/jdk/pull/4156