Add logging of various important graphics events

There are 16 events logged in the event log:
SF_APP_DEQUEUE_BEFORE
SF_APP_DEQUEUE_AFTER
SF_APP_LOCK_BEFORE
SF_APP_LOCK_AFTER
SF_APP_QUEUE

SF_REPAINT
SF_COMPOSITION_COMPLETE
SF_UNLOCK_CLIENTS
SF_SWAP_BUFFERS
SF_REPAINT_DONE

SF_FB_POST_BEFORE
SF_FB_POST_AFTER
SF_FB_DEQUEUE_BEFORE
SF_FB_DEQUEUE_AFTER
SF_FB_LOCK_BEFORE
SF_FB_LOCK_AFTER

all events log the buffer conserned and a timestamp in microseconds.

by default the logging is not enabled, to turn it on:
adb shell service call SurfaceFlinger 1006 i31 1
adb shell setprop debug.graphic_log 1

The effect is immediate in SurfaceFlinger, but applications need to be
restarted.

Change-Id: Ifc2e31f7aed072d9a7dede20ff2ce59231edbec1