JNAerator: Generate Android-friendly code for direct mapping

Avoid error “The SecurityManager implementation on this platform is broken; you must explicitly provide the class to register” due to stub SecurityManager on Android as described in https://github.com/twall/jna/issues/218 .
Merge pull request #432 from cwalther/android

JNAerator: Generate Android-friendly code for direct mapping (pull request from Christian Walther)