RFR: JDK-8312612: handle WideCharToMultiByte return values [v2]

[Matthias Baesken]

> The function WideCharToMultiByte is used at a number of places of the JDK codebase for conversion purposes.
> Unfortunately, the function might fail because of various reasons, so the return value must be checked to avoid undefined behavior or even crashes.
> see
> https://learn.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-widechartomultibyte
> especially
> https://learn.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-widechartomultibyte#return-value
> 
> At most places in the coding the return values are already checked, but some are missing.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  small adjustments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15015/files
  - new: https://git.openjdk.org/jdk/pull/15015/files/cf5e9a67..3cf91afb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15015&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15015&range=00-01

  Stats: 4 lines in 2 files changed: 1 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15015.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15015/head:pull/15015

PR: https://git.openjdk.org/jdk/pull/15015