RFR: 8278891: G1: Call reset in G1RegionMarkStatsCache constructor [v2]

[Hamlin Li]

> Currently, G1RegionMarkStatsCache constructor does not call G1RegionMarkStatsCache::reset(), it depends on user to call it explicitly to make sure it works well and without crash in G1RegionMarkStatsCache::evict(uint idx).
> 
> In fact G1RegionMarkStatsCache constructor should call G1RegionMarkStatsCache::reset() to ensure its valid initial state.
> 
> ( I met this issue when I tried to reuse this class to implement some parallel cache when improve the parallelism of evacuation failure. )

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

  Albert review

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6861/files
  - new: https://git.openjdk.java.net/jdk/pull/6861/files/4855018c..fc5f4ad5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6861&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6861&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6861.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6861/head:pull/6861

PR: https://git.openjdk.java.net/jdk/pull/6861