RFR: New arraycopy atomicity tests

[Aleksey Shipilev]

New tests to observe (non-)atomicity of arraycopy

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Commit messages:
 - Fix T1/T2 order in descriptions
 - Arraycopy atomicity tests

Changes: https://git.openjdk.java.net/jcstress/pull/3/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=3&range=00
  Stats: 202 lines in 4 files changed: 202 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/3.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/3/head:pull/3

PR: https://git.openjdk.java.net/jcstress/pull/3