RFR: JDK-8308028 Replace more uses of System.getProperty("os.name") with PlatformUtil calls [v4]

[Carl Döbbelin]

> replaced implementation of OS checks in HostUtils with calls of PlatformUtil

Carl Döbbelin has updated the pull request incrementally with one additional commit since the last revision:

  removed HostUtils

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1134/files
  - new: https://git.openjdk.org/jfx/pull/1134/files/a14bab71..6a637dec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1134&range=03
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1134&range=02-03

  Stats: 106 lines in 8 files changed: 5 ins; 83 del; 18 mod
  Patch: https://git.openjdk.org/jfx/pull/1134.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1134/head:pull/1134

PR: https://git.openjdk.org/jfx/pull/1134