RFR: New field conflict tests

[Aleksey Shipilev]

Chapter 0.a does not test what happens on conflicting stores (sometimes write-write data race). Need to add a few very
basic tests

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Commit messages:
 - New field conflict tests

Changes: https://git.openjdk.java.net/jcstress/pull/4/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=4&range=00
  Stats: 71 lines in 2 files changed: 71 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/4.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/4/head:pull/4

PR: https://git.openjdk.java.net/jcstress/pull/4