RFR: 8265100: (fs) WindowsFileStore.hashCode() should read cached hash code once [v2]

[Brian Burkhalter]

> Please review this small request to clean up `WindowsFileStore.hashCode()`.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8265100: Make hashCode non-volatile

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3445/files
  - new: https://git.openjdk.java.net/jdk/pull/3445/files/e3bc63c2..faa48706

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3445&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3445&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3445.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3445/head:pull/3445

PR: https://git.openjdk.java.net/jdk/pull/3445