Accumulate frame tpl stats and pass through rate control api

Accumulate frame tpl stats and pass through rate control api

Tpl stats is computed at the beginning of encoding the altref
frame. We aggregate tpl stats of all blocks for every frame of
the current group of picture.

After the altref frame is encoded, the tpl stats is passed through
the encode frame result to external environment.
Change-Id: I2284f8cf9c45d35ba02f3ea45f0187edbbf48294