RFR: 8361299: (bf) CharBuffer.getChars(int,int,char[],int) violates pre-existing specification

[Brian Burkhalter]

Modify `CharBuffer.getChars` to respect the class level specification that the provided buffer offset `srcBegin` is relative to the buffer's current position.

-------------

Commit messages:
 - 8361299: (bf) CharBuffer.getChars(int,int,char[],int) violates pre-existing specification

Changes: https://git.openjdk.org/jdk/pull/26104/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26104&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361299
  Stats: 24 lines in 2 files changed: 9 ins; 3 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/26104.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26104/head:pull/26104

PR: https://git.openjdk.org/jdk/pull/26104