[jdk17u-dev] RFR: 8294399: (ch) Refactor some methods out of sun.nio.ch.UnixFileDispatcherImpl

[Shruthi]

Signed-off-by: Shruthi [Shruthi.Shruthi1 at ibm.com](mailto:Shruthi.Shruthi1 at ibm.com)

OpenJDK PR : https://github.com/openjdk/jdk/pull/10434
OpenJDK bug : https://bugs.openjdk.org/browse/JDK-8294399

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Commit messages:
 - Backport d6678952a6de4e5435dab65e7029021832454857

Changes: https://git.openjdk.org/jdk17u-dev/pull/3631/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3631&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294399
  Stats: 232 lines in 8 files changed: 157 ins; 62 del; 13 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3631.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3631/head:pull/3631

PR: https://git.openjdk.org/jdk17u-dev/pull/3631