send classname to javah as list

When using multiple jni classes, the `ndkJavah` task failes with following exception.

    Exception in thread "main" java.lang.IllegalArgumentException: Not a valid class name: net.surina.soundtouch.SoundTouch karuta.hpnpwd.audio.OggVorbisDecoder

This is because classname which passed to `javah` is a space joined classname. This pull request solves the problem.