RFR: JDK-8260335: [macos] Running app using relative path causes problems

[Andy Herrick]

Fixing FileUtils.dirname() to skip over "/.".

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Commit messages:
 - JDK-8260335: [macos] Running app using relative path causes problems on MacOS

Changes: https://git.openjdk.java.net/jdk/pull/2260/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2260&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260335
  Stats: 10 lines in 1 file changed: 8 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2260.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2260/head:pull/2260

PR: https://git.openjdk.java.net/jdk/pull/2260