RFR: 8233421: Upgrade to Visual Studio 2017 version 15.9.16

[Kevin Rushforth]

[JDK-8233421](https://bugs.openjdk.java.net/browse/JDK-8233421)

This bumps the windows compiler version to VS2017 version 15.9.16 to match JDK 14. I have run a full build and test, including WebKit and media.

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Commits:
 - aab19fa8: 8233421: Upgrade to Visual Studio 2017 version 15.9.16

Changes: https://git.openjdk.java.net/jfx/pull/40/files
 Webrev: https://webrevs.openjdk.java.net/jfx/40/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233421
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/40.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/40/head:pull/40

PR: https://git.openjdk.java.net/jfx/pull/40