Revert "Removing this_frame_stats member from TWO_PASS struct."

Use of stack frame variable "fps" beyond the lifetime of the function.

fps is sent as a paremeter to output_stats and stored in the
packet holding this encoded frame. This has scope beyond the
lifetime of the calling function.

This reverts commit 3f95a230

Change-Id: Icd8e14b3d7dd733590ada12e619b9dce95b6b0f5