RFR: JDK-8294837: unify Windows 2019 version check in os_windows and java_props_md

[Matthias Baesken]

Currently the buildNumber check for Windows 2019 server differs in os_windows.cpp and java_props_md.c ( java_props_md.c still checks pre GA versions , this is probably not necessary any more ).
The check should be unified.

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Commit messages:
 - unify Win 2019 build number check in os_windows.cpp and java_props_md.c

Changes: https://git.openjdk.org/jdk/pull/10570/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10570&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294837
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10570.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10570/head:pull/10570

PR: https://git.openjdk.org/jdk/pull/10570