RFR: 8302659: Modernize Windows native code for NetworkInterface

[Rich DiCroce]

Improves performance and correctness, as discussed on the net-dev mailing list.

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Commit messages:
 - Fix whitespace issues
 - Remove executable bit from NetworkInterface.c
 - Rewrite Windows native code for NetworkInterface to improve performance and correctness

Changes: https://git.openjdk.org/jdk/pull/12593/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12593&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302659
  Stats: 2347 lines in 5 files changed: 302 ins; 1803 del; 242 mod
  Patch: https://git.openjdk.org/jdk/pull/12593.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12593/head:pull/12593

PR: https://git.openjdk.org/jdk/pull/12593