RFR: 8306374: (bf) Improve performance of DirectCharBuffer::append(CharSequence[,int,int]) [v3]

[Brian Burkhalter]

> Use `getChars()` to copy characters to an intermediate local `char[]` array and then `putArray()` to copy the chars into the buffer itself.

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

  8306374: Remove superfluous csq == null check

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13522/files
  - new: https://git.openjdk.org/jdk/pull/13522/files/d81313a6..52c94582

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13522&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13522&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13522.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13522/head:pull/13522

PR: https://git.openjdk.org/jdk/pull/13522