RFR: 8264400: (fs) WindowsFileStore equality depends on how the FileStore was constructed

[Brian Burkhalter]

Please consider this change to make `sun.nio.fs.WindowsFileStore.equals()` return `true` if the root strings of the two objects are equal under case insensitive comparison, and the two `WindowsFileStore`s have the same volume information.

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Commit messages:
 - 8264400: (fs) WindowsFileStore equality depends on how the FileStore was constructed

Changes: https://git.openjdk.java.net/jdk/pull/3279/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3279&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264400
  Stats: 23 lines in 2 files changed: 19 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3279.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3279/head:pull/3279

PR: https://git.openjdk.java.net/jdk/pull/3279