RFR: 8273922: (fs) UserDefinedFileAttributeView doesn't handle file names that are just under the MAX_PATH limit (win)

[Brian Burkhalter]

Modify `sun.nio.fs.WindowsUserDefinedFileAttributeView.join(WindowsPath,String)` to handle file names which exceed the limit.

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Commit messages:
 - 8273922: (fs) UserDefinedFileAttributeView doesn't handle file names that are just under the MAX_PATH limit (win)

Changes: https://git.openjdk.java.net/jdk/pull/5594/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5594&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273922
  Stats: 59 lines in 2 files changed: 45 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5594.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5594/head:pull/5594

PR: https://git.openjdk.java.net/jdk/pull/5594