RFR: 8292279: (fs) Use try-with-resources to release NativeBuffer

[Andrey Turbanov]

Since [JDK-8260966](https://bugs.openjdk.org/browse/JDK-8260966), NativeBuffer implements AutoCloseable interface.
Now we can use try-with-resources statements to simplify code.

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Commit messages:
 - [PATCH] Use try-with-resources to release NativeBuffer

Changes: https://git.openjdk.org/jdk/pull/9794/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9794&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292279
  Stats: 176 lines in 13 files changed: 6 ins; 112 del; 58 mod
  Patch: https://git.openjdk.org/jdk/pull/9794.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9794/head:pull/9794

PR: https://git.openjdk.org/jdk/pull/9794