RFR: 8265031: Change default macOS min version for x86_64 to 10.12 and aarch64 to 11.0 [v2]

[Kevin Rushforth]

> As noted in the JBS bug, the minimum macOS version on which JavaFX will run is currently set to 10.10 in `mac.gradle`. macOS 10.10 is many years out of support, so we should update this minimum. Further, macOS / aarch64 (aka arm64) requires macOS 11.0 as a minimum in order to run.
> 
> The JDK recently updated their minimum for x86_64 to 10.12 and for aarch64 to 11.0. See [make/autoconf/flags.m4#L136](https://github.com/openjdk/jdk/blob/627ad9fe22a153410c14d0b2061bb7dee2c300af/make/autoconf/flags.m4#L136).
> 
> This PR will do the same for JavaFX.
> 
> To determine whether we are building on `aarch64`, I check the `TARGET_ARCH` property for either `aarch64` or `arm64`, since we currently use the latter for our builds, although we should proably update our build to consistently use `aarch64` everywhere, and map that to `arm64` on usage where required by native tools.

Kevin Rushforth has updated the pull request incrementally with one additional commit since the last revision:

  update to use isAarch64 per review comments

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/462/files
  - new: https://git.openjdk.java.net/jfx/pull/462/files/218459e2..8980ab6d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=462&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=462&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/462.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/462/head:pull/462

PR: https://git.openjdk.java.net/jfx/pull/462