automake: Don't include Android Makefiles in the release tarball

Currently only some Android Makefiles are included in the release tarball.
To be more consistent one could either add the remaining files or don't
ship Android Makefiles altogether.

According to Emil the Android folk doesn't use our release tarballs.
Thus it makes sense to remove those files from distribution which also
means less work for maintenance in the future.

Suggested-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Andreas Boll <andreas.boll.dev@gmail.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>