RFR: 8213177: GlobalCounter::CSContext could be an enum class [v2]

[Harold Seigel]

> Please review this small change for JDK-8213177.  The change was regression tested with Mach5 tiers 1 and 2 on Linux, Windows, and Mac OS, and Mach5 tiers 3-5 on Linux x64.
> 
> Thanks, Harold

Harold Seigel has updated the pull request incrementally with one additional commit since the last revision:

  Fix comments

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2895/files
  - new: https://git.openjdk.java.net/jdk/pull/2895/files/a7820525..32acbaa1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2895&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2895&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2895.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2895/head:pull/2895

PR: https://git.openjdk.java.net/jdk/pull/2895