RFR: 8287843: File::getCanonicalFile doesn't work for \?\C:\ style paths DOS device paths

[Brian Burkhalter]

In the Windows implementation of java.io.File.getCanonicalPath, strip any long path or UNC prefix before canonicalizing the remainder of the pathname.

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Commit messages:
 - 8287843: File::getCanonicalFile doesn't work for \?\C:\ style paths DOS device paths

Changes: https://git.openjdk.org/jdk/pull/15603/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15603&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287843
  Stats: 65 lines in 2 files changed: 54 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/15603.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15603/head:pull/15603

PR: https://git.openjdk.org/jdk/pull/15603