RFR: 8269967: JavaFX should fail fast on macOS below minimum version

[Kevin Rushforth]

This PR implements a version check in the JavaFX runtime initialization code on macOS to ensure that the platform is running a version of macOS that is at or above the minimum version. If the platform is below the specified minimum, the JavaFX initialization code throws an exception.

The minimum version is passed from the `mac.gradle` file to the Mac glass code as a pair of build time constants, which are compared at runtime to the platform version.

Notes to reviewers:

* In case anyone is interested, the first commit has some debug logging which will print the minimum version and the detected platform version. I removed them with the second commit.

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Commit messages:
 - Remove debug logging
 - 8269967: JavaFX should fail fast on macOS below minimum version

Changes: https://git.openjdk.java.net/jfx/pull/567/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=567&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269967
  Stats: 35 lines in 2 files changed: 34 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/567.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/567/head:pull/567

PR: https://git.openjdk.java.net/jfx/pull/567