RFR: 8273185: Rename the term "atomic" in ReferenceProcessor

[Thomas Schatzl]

Hi all,

  please review this suggestion to rename the term "atomic" in the `ReferenceProcessor` class to "concurrent"/"stw" to avoid the confusion with Atomic operations.

It's a smaller change than expected, which is good, but also might question the need for this change. I grepped for "atomic" in the reference processor sources and hopefully got everything.

Testing: tier1-5

Thanks,
  Thomas

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Commit messages:
 - Rename atomic to concurrent/stw

Changes: https://git.openjdk.java.net/jdk/pull/5397/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5397&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273185
  Stats: 36 lines in 4 files changed: 1 ins; 2 del; 33 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5397.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5397/head:pull/5397

PR: https://git.openjdk.java.net/jdk/pull/5397