gradle apps fails to build on linux-arm platforms

After the fix for JDK-8134716 the build is broken on linux-arm platforms.

To reproduce, run the following on a linux-arm configuration:

$ gradle -PCOMPILE_TARGETS=armv6hf apps

[ant:javac] Compiling 2 source files to 9-dev/label/linux-armv6-91/rt/apps/tests/HelloTest/build/classes
9-dev/label/linux-armv6-91/rt/apps/tests/HelloTest/src/hellotest/HelloFPS.java:28: error: package javafx.animation does not exist
import javafx.animation.KeyFrame;
                       ^
...