RFR: 8278276: G1: Refine naming of G1GCParPhaseTimesTracker::_must_record [v2]

[Hamlin Li]

> This is a trivial improvement to refine the naming of G1GCParPhaseTimesTracker::_must_record to _initial_record.

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  use allow_multiple_record

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6714/files
  - new: https://git.openjdk.java.net/jdk/pull/6714/files/4da989d4..fee80489

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6714&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6714&range=00-01

  Stats: 10 lines in 3 files changed: 2 ins; 2 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6714.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6714/head:pull/6714

PR: https://git.openjdk.java.net/jdk/pull/6714