framedata: fix license header
frame: move rate control data to FrameData, cleanup variable names
framedata: change 'structure of arrays' to 'array of structures' for RC stats

This uses fewer mallocs, fewer memsets, and generally better data locality. It
doesn't hurt that the code is more readable.
rc: use curEncData.m_numCUsInFrame

Note that the CU count was wrongly calculated before as height * height,
broken by me a couple days ago in 14d5345e257a