RFR: 8269968: [REDO] Bump minimum version of macOS for x64 to 10.12

[Kevin Rushforth]

The fix for [JDK-8266743](https://bugs.openjdk.java.net/browse/JDK-8266743) (crash on macOS 10.11) -- was to partially revert [JDK-8265031](https://bugs.openjdk.java.net/browse/JDK-8265031), and lower the minimum macOS version for x64 back to 10.10 in JavaFX 17. We should bump it back to 10.12 in JavaFX 18.

This will be done in connection with [JDK-8269967](https://bugs.openjdk.java.net/browse/JDK-8269967), PR #567, which will provide a fail-fast when attempting to run on an older version of macOS than the minimum. I will not integrate this PR until after that one is integrated.

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Commit messages:
 - 8269968: [REDO] Bump minimum version of macOS for x64 to 10.12

Changes: https://git.openjdk.java.net/jfx/pull/570/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=570&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269968
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/570.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/570/head:pull/570

PR: https://git.openjdk.java.net/jfx/pull/570