Layoutlib: use int[] wrapper to use as map keys.

This fixes the SlidingDrawer that failed to load.

For some reason, in case of the SlidingDrawer, when the constructor
uses android.R.styleable.SlidingDrawer it's the same values but not
the same instance as the array read from android.R through reflection.

So what works for all other widgets, and has worked since the very first
layoutlib isn't working anymore, and we'll now have to use a wrapper
similarly to what we use in ADT in the project callback.

We should probably provide a single int[] wrapper class in layoutlib
API for all to use.

Change-Id: I4d7d038540f8a24541a588696f1059a020b589e5