RFR: 8305809: (fs) Review obsolete Linix kernel dependency on os.version (Unix kernel 2.6.39)

[Brian Burkhalter]

Remove contingency on Linux kernel version of return value of `LinuxFileStore::supportsFileAttributeView` for ext4 file systems.

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Commit messages:
 - 8305809: (fs) Review obsolete Linix kernel dependency on os.version (Unix kernel 2.6.39)

Changes: https://git.openjdk.org/jdk/pull/13412/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13412&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305809
  Stats: 13 lines in 1 file changed: 0 ins; 10 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/13412.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13412/head:pull/13412

PR: https://git.openjdk.org/jdk/pull/13412