RFR: 8262844: (fs) FileStore.supportsFileAttributeView might return false negative in case of ext3 [v2]

[Arno Zeller]

> FileStore.supportsFileAttributeView might return a wrong value for ext3 mounts. In case of newer Linux distributions the extended attributes are enabled by default for ext3 mounts and do not show up /proc/mounts.
> Currently the mount table is parsed to determine whether the mount options contain user_xattr  or nouser_xattr. In case of neither entry it is expected that extended attributes are not supported on ext3. 
> 
> This change will for ext3 always probe the fs if none of the options above are found. This should ensure that we return the right value.

Arno Zeller has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Removed special handling for ext4 too
 - Merge remote-tracking branch 'upstream/master' into LinuxFileStore
 - Fix ext3 detection in LinuxFileStore

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2778/files
  - new: https://git.openjdk.java.net/jdk/pull/2778/files/5fffc8d5..429663ab

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2778&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2778&range=00-01

  Stats: 4540 lines in 166 files changed: 2670 ins; 1390 del; 480 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