[jdk17] RFR: 8269074: (fs) Files.copy fails to copy from /proc on some linux kernel versions [v2]

[Brian Burkhalter]

> On Linux, if while executing `java.nio.file.Files.copy(Path,Path,CopyOption...)` the native function `sendfile(2)` fails with `EINVAL`, fall back to transferring via user-space buffers.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8269074: Also fall back to user space buffer for ENOSYS from sendfile(2)

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Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/128/files
  - new: https://git.openjdk.java.net/jdk17/pull/128/files/4886f787..78a7c27a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=128&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=128&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/128.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/128/head:pull/128

PR: https://git.openjdk.java.net/jdk17/pull/128