RFR: 8265989: System property for the native character encoding name [v2]

[Naoto Sato]

> After some internal discussion, we thought it was good to expose the native environment's default character encoding, which Charset.defaultCharset() is currently based on. This way applications will have a better migration path after the [JEP 400](https://openjdk.java.net/jeps/400) is implemented, in which Charset.defaultCharset() will return UTF-8, but the value of this new system property will remain intact. A [CSR](https://bugs.openjdk.java.net/browse/JDK-8266075) has been filed with more detailed information.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Added internal getter for native.encoding

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3777/files
  - new: https://git.openjdk.java.net/jdk/pull/3777/files/fa5246c8..e76ff410

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3777&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3777&range=00-01

  Stats: 16 lines in 1 file changed: 15 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3777.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3777/head:pull/3777

PR: https://git.openjdk.java.net/jdk/pull/3777