pm: Add persist property to enable lazy dexopt

 * Add "persist.sys.lazy.dexopt" property to enable lazy dexopt
   on userdebug builds.  As much as I enjoy these 20 minute
   dexopt sessions, I prefer instant gratification.

Change-Id: I568692f04d67c3c0a1a138fb724eda41e24b1235
[base] long press back to kill configurable timeout (1/2)

Forward ported from crDroid kk