RFR: 8262844: FileStore.supportsFileAttributeView might return false negative in case of ext3

[Arno Zeller]

8262844: FileStore.supportsFileAttributeView might return false negative in case of ext3

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Commit messages:
 - Fix ext3 detection in LinuxFileStore

Changes: https://git.openjdk.java.net/jdk/pull/2778/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2778&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262844
  Stats: 7 lines in 1 file changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2778.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2778/head:pull/2778

PR: https://git.openjdk.java.net/jdk/pull/2778