RFR: 8306374: (bf) Improve performance of DirectCharBuffer::append(CharSequence[,int,int]) [v5]

[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 with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - 8306374: Remove checkSession() from appendChars(); augment test
 - Merge
 - 8306374: Replace checkFromIndexSize() with checkFromToIndex()
 - 8306374: Remove superfluous csq == null check
 - 8306374: Add explicit bounds check; allocate less memory if possible
 - 8306374: (bf) Improve performance of DirectCharBuffer::append(CharSequence[,int,int])

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13522/files
  - new: https://git.openjdk.org/jdk/pull/13522/files/6455212f..739c33ab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13522&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13522&range=03-04

  Stats: 30869 lines in 572 files changed: 23959 ins; 4463 del; 2447 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