RFR: 8275287: Relax memory ordering constraints on updating instance class and array class counters

[Zhengyu Gu]

The same as JDK-8275287, the counters only need atomic guarantee,  so that, their memory constraints can be relaxed.

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Commit messages:
 - Fix assert
 - v0

Changes: https://git.openjdk.java.net/jdk/pull/5970/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5970&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275287
  Stats: 10 lines in 1 file changed: 1 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5970.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5970/head:pull/5970

PR: https://git.openjdk.java.net/jdk/pull/5970