RFR: 8292562: (fc) Use copy_file_range in FileChannel::transferTo on Linux

[Brian Burkhalter]

Add `copy_file_range(2)` to the native Linux implementation of `FileChannel::transferTo`.

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Commit messages:
 - 8292562: (fc) Use copy_file_range in FileChannel::transferTo on Linux

Changes: https://git.openjdk.org/jdk/pull/9925/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9925&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292562
  Stats: 21 lines in 1 file changed: 20 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9925.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9925/head:pull/9925

PR: https://git.openjdk.org/jdk/pull/9925