v44: Several performance improvements

The main change is that the original method is now saved in insns.
This does not only save a lookup, but we can also save additional
information with it. We save the Method object (to avoid creating a
new one every time) and an arbitrary object (which is filled with
references to callbacks, return type and parameter types by XposedBridge.

We also do the lookup of the Object class just once.

Requires changes in XposedBridge to work.
Implement invokeOriginalMethodNative as internal native function, no JNI
Convert xposedCallHandler to non-JNI native as well

Thanks to this, we no longer need to manage thread status and reference
tracking ourself, which is faster and more stable.
Pass-through the pointer to the original method

This avoids that we need to convert the reflection object back to the
methodId that we already know in xposedCallHandler(). This saves another
microsecond on my phone.
Enforce using the Dalvik runtime library

As ART is not supported (yet?), disable it when Xposed is active to
avoid bootloops.