RFR: 8371436: (fs) java/nio/file/FileStore/Basic.java fails on macOS platform due to assertTrue(!store.equals(prev));

[Brian Burkhalter]

In `BsdNativeDispatcher.fsstatEntry()`, initialize the `UnixMountEntry` field `dev`, which propagates to `UnixFileStore` and is used in the latter's `equals` method, which `BsdFileStore` does not override.

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Commit messages:
 - 8371436: (fs) java/nio/file/FileStore/Basic.java fails on macOS platform due to assertTrue(!store.equals(prev));

Changes: https://git.openjdk.org/jdk/pull/28205/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28205&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371436
  Stats: 11 lines in 1 file changed: 10 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28205.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28205/head:pull/28205

PR: https://git.openjdk.org/jdk/pull/28205