AbsListView: add option to disable scrolling cache (2/2)

Ported from gingerbread

scrolling cache can cause performance lag due to GC
allow user to enable/disable/force scrolling cache on the fly
via Settings > Performance > Scrolling cache

Change-Id: I6826a7e2036f2fc4f6044e2c197c38c278bcdf21

Conflicts:
	res/values/cm_arrays.xml
	res/values/cm_strings.xml
	res/xml/performance_settings.xml
	src/com/android/settings/cyanogenmod/PerformanceSettings.java