RFR: 8292016: Rework JLI_ReportErrorMessageSys [v9]

[Julian Waters]

> Second attempt at resolving [JDK-8292016](https://bugs.openjdk.org/browse/JDK-8292016) with a less intrusive approach this time 
> 
> Side note: While it might be preferred to remove this entirely, other areas of the JDK also use the same flawed logic, and removing this would simply push the issue elsewhere. Fixing this might result in a solution which can be used in those areas in the future.

Julian Waters has updated the pull request incrementally with two additional commits since the last revision:

 - Shift conflict check to end
 - Conflict check can be folded

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9870/files
  - new: https://git.openjdk.org/jdk/pull/9870/files/a1fc9cd3..0c07454b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9870&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9870&range=07-08

  Stats: 36 lines in 1 file changed: 15 ins; 13 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/9870.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9870/head:pull/9870

PR: https://git.openjdk.org/jdk/pull/9870