RFR: 8292989: Avoid dynamic memory in AsyncLogWriter

[Xin Liu]

8292989: Avoid dynamic memory in AsyncLogWriter

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

Commit messages:
 - clean up code.
 - double async-logging buffer to ensure that -Xlog:all=debug doesn't drop
 - refector buffer.push_back
 - replace linked-list with pre-allocated ping-pong buffer.

Changes: https://git.openjdk.org/jdk/pull/10092/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10092&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292989
  Stats: 353 lines in 4 files changed: 154 ins; 169 del; 30 mod
  Patch: https://git.openjdk.org/jdk/pull/10092.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10092/head:pull/10092

PR: https://git.openjdk.org/jdk/pull/10092