RFR: Samples for race condition

[Michael Mirwaldt]

I have created two more samples:

- one sample for read-modify-write-sequences
- one sample for check-then-react-sequences

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Commit messages:
 - force a commit with my github user mmirwaldt-openjdk to get rid of the OCA label
 - gave state annotation its own line
 - corrected copyright
 - improved code again by getting rid of AtomicBoolean and AtomicInteger
 - improved code by applying ideas from another PR
 - Two more samples:

Changes: https://git.openjdk.java.net/jcstress/pull/88/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=88&range=00
  Stats: 145 lines in 2 files changed: 145 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/88.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/88/head:pull/88

PR: https://git.openjdk.java.net/jcstress/pull/88