AbsListView: add option to disable scrolling cache (1/2)
Ported from gingerbread with logging removed

scrolling cache (discard?) can cause performance lag due to GC
allow user to enable/disable/force scrolling cache on the fly
inspired by AndroidON, http://forum.xda-developers.com/showthread.php?t=1411317

Change-Id: Ibced70a11831c0f188bbc82f3c3cedeeb44ac689