I was mistaken recently, thinking that cpal's dev-dependency on ndk-glue
was somehow being inherited by the example. Actually the real issue was
that cpal 0.13.5 has a regular _dependency_ on ndk-glue, which is a much
simpler explanation for why we were seeing a crash.
This updates the example to just use the master branch of cpal, which we'll
need until there is a new release of cpal.
Based on the android example that's in the cpal repo, this test plays
a 440hz sine wave and is based on GameActivity
Note: this requires a workaround branch for cpal that comments out
a dev-dependency on ndk-glue that cpal has for its android example.
This is needed because Cargo is spuriously propagating this dev
dependency outside of the cpal package (which leads to a crash)
Robert Bragg