RFR: 8311291: Enable creation of NonInterleavingLogStream from LogTarget [v2]

[Johan Sjölen]

> Hi,
> 
> This patch enables the same kind of construction method for NILS that we already have for regular LogStream. We need to do some ugly changes to make it work, but it's so much more ergonomic for usage sites that I think it's worth it.

Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:

 - Move cheating out to friend classes instead
 - Adjust

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14769/files
  - new: https://git.openjdk.org/jdk/pull/14769/files/6a29adc4..86a205b5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14769&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14769&range=00-01

  Stats: 16 lines in 3 files changed: 7 ins; 4 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/14769.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14769/head:pull/14769

PR: https://git.openjdk.org/jdk/pull/14769