Adjust mBiggerTouchSlopSquare to the suitable value

If the scaling factor is larger than 1.0 (i.e. 1.5),
then mTouchSlopSquare(576) is bigger than mBiggerTouchSlopSquare(400).
The double tap condition should be bigger than a single tap's one.
This causes the fail of the following CTS test cases in the device has
over 240 density.
- android.view.cts.GestureDetectorTest
  * testOnTouchEvent
- android.view.cts.GestureDetector_SimpleOnGestureListenerTest
  * testSimpleOnGestureListener
To fix this issue, I'll add a new public method
ViewConfiguration#getScaledLargeTouchSlop() then the value returned
from that method is used as a slop area of mLargeTouchSlop.

Change-Id: I0e61c13670e1300be1ccf45a89ef89410496fb48