RFR: 8280881: (fs) UnixNativeDispatcher.close0 may throw UnixException [v3]

[Brian Burkhalter]

> Re-specify `sun.nio.fs.UnixNativeDispatcher.close0()` to throw `sun.nio.fs.UnixException` and modify callers either to ignore it or to rethrow it as an `IOException`, as appropriate.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8280881: Add close variants to UnixNativeDispatcher; clean up close use sites

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7467/files
  - new: https://git.openjdk.java.net/jdk/pull/7467/files/0e7b72fb..546ec82f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7467&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7467&range=01-02

  Stats: 163 lines in 9 files changed: 44 ins; 85 del; 34 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7467.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7467/head:pull/7467

PR: https://git.openjdk.java.net/jdk/pull/7467