RFR: 8292016: Rework JLI_ReportErrorMessageSys

[Julian Waters]

Second attempt at resolving [JDK-8292016](https://bugs.openjdk.org/browse/JDK-8292016) with a less intrusive approach this time (Clearing the error after the call, which is done in other areas of the JDK as well)

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.

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Commit messages:
 - Split Windows API errors out of JLI_ReportErrorMessageSys
 - Whitespace
 - Implement platform specific sections
 - Whitespace
 - Comment should mention usage risks
 - First rework

Changes: https://git.openjdk.org/jdk/pull/9870/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9870&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292016
  Stats: 108 lines in 5 files changed: 72 ins; 21 del; 15 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