RFR: 8256825: Cleanup WeakProcessorPhaseTimes

[Kim Barrett]

Please review this cleanup of WeakProcessorPhaseTimes.  After JDK-8212879
there are several functions declared but no longer used or even defined.
There are also some naming conventions that no longer make sense.

Testing:
mach5 tier1

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Commit messages:
 - cleanup

Changes: https://git.openjdk.java.net/jdk/pull/1367/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1367&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256825
  Stats: 14 lines in 2 files changed: 0 ins; 4 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1367.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1367/head:pull/1367

PR: https://git.openjdk.java.net/jdk/pull/1367