RFR: 8233451: (fs) Files.newInputStream() cannot be used with character special files [v4]

[Brian Burkhalter]

> Add `isOther` and `available` methods to `FileChannelImpl` and the interfaces to native code and use these in `ChannelInputStream` to work around cases where a wrapped `FileChannelImpl` is not really seekable.

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

  8233451: Add tests for read{All,N}Bytes

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21508/files
  - new: https://git.openjdk.org/jdk/pull/21508/files/492659f6..ead1b59b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21508&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21508&range=02-03

  Stats: 125 lines in 1 file changed: 116 ins; 2 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/21508.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21508/head:pull/21508

PR: https://git.openjdk.org/jdk/pull/21508