RFR: 8265425: Hard failure when building OpenJFX for Linux AArch64

[Tor (torbuntu)]

For building on aarch64 linux systems we need it added to the buuld.gradle to stop ignoring it.

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Commit messages:
 - Add aarch64 support to linux

Changes: https://git.openjdk.java.net/jfx/pull/465/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=465&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265425
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/465.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/465/head:pull/465

PR: https://git.openjdk.java.net/jfx/pull/465