More checks in JNI RegisterNatives

Throws NoSuchMethodError (and returns JNI_ERR) when given method name, method
signature or native function is null.

Bug: https://code.google.com/p/android/issues/detail?id=72293
Bug: 15886341
Change-Id: I1c0582d54031eaa58a6025a2417d65090a2a622a
2 files changed