RFR: 8274190: Use String.equals instead of String.compareTo in jdk.internal.jvmstat [v2]

[Andrey Turbanov]

> In several places, String.compareTo was _compared_ with 0 ( via `== 0` or `!= 0`).
> Instead of this, we can use String.equals calls. `String.equals` is faster and shorter.

Andrey Turbanov has updated the pull request incrementally with one additional commit since the last revision:

  8274190: Use String.equals instead of String.compareTo in jdk.internal.jvmstat
  cleanup redundant parentheses

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5638/files
  - new: https://git.openjdk.java.net/jdk/pull/5638/files/f5e58485..167ccfe1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5638&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5638&range=00-01

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5638.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5638/head:pull/5638

PR: https://git.openjdk.java.net/jdk/pull/5638