RFR: 8292279: (fs) Use try-with-resources to release NativeBuffer [v2]

[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.

Andrey Turbanov has updated the pull request incrementally with one additional commit since the last revision:

  8292279: (fs) Use try-with-resources to release NativeBuffer
  
  apply Alan's suggestion

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9794/files
  - new: https://git.openjdk.org/jdk/pull/9794/files/37b6d13e..1784e4ee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9794&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9794&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 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