ADT/Layoutlib: implement Canvas.concat(Matrix)

This prevented ImageView from making proper use of ScaleType.

Also fixed Canvas.getSaveCount() that returned the wrong
value and Matrix.getTransform() which used the wrong order
for the AffineTransform constructor!!

Bug: 2364564

Change-Id: I78babf4aa6689440e52ad06b1473f75b20eb66da