RFR: 8327410: Add hostname option for UL file names [v4]

[Fredrik Bredberg]

> Added %hn as way to make the Unified Logging file name include the host name.
> This is done in line with the already existing %p for pid, and %t for time stamp.
> 
> Also the %hn decorator is already used to prepend the host name to each log line. See: The [JDK-8148219](https://bugs.openjdk.org/browse/JDK-8148219).
> 
> Example: `java -Xlog:gc+init:file=frbr_%hn.%p.%t.log -version`
> 
> Tested tier1-tier5.

Fredrik Bredberg 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 seven additional commits since the last revision:

 - Merge branch 'master' into 8327410_add_hostname_option_to_ul_filename
 - Merge branch 'master' into 8327410_add_hostname_option_to_ul_filename
 - Updated man page java.1
 - Update after review
 - Update after review
 - Get the hostname only if the user explicitly requests it
 - 8327410: Add hostname option for UL file names

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18153/files
  - new: https://git.openjdk.org/jdk/pull/18153/files/203ec37e..0b8a6198

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18153&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18153&range=02-03

  Stats: 453802 lines in 3966 files changed: 33068 ins; 92825 del; 327909 mod
  Patch: https://git.openjdk.org/jdk/pull/18153.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18153/head:pull/18153

PR: https://git.openjdk.org/jdk/pull/18153