deperecate Cursor requery() and sa, Loader should be used instead

the warning printed currently "do requery on background thread"
is not that useful in processes such as gapps, acore.
to reduce the deluge of bugs assigned to me, I think a simple
deprecation warning is better.

Change-Id: I7a1129ea889f10e72895092a3cdd48cc96d0d1f0