Function encode_rtc_frame_internal() and encode_frame_internal() only
differed by a couple of speed features, this commit relocation those
difference into the setup of speed features and merged two functions
into one to remove duplication.

It also fixed a subtle bug super_fast_rtc was used before it was
initialized.

Change-Id: I234a5a1d11a4450930e5b4943dbab434208d5030

-Properly set the average frame size for each layer.

-Allow each layer to update its average/last Q stats after encoding.

-Initialize for some layer context variables.

Change-Id: Iaa37d144fcf4f30ff4283a4e8db8b9ca8bf4c815

Change-Id: I467b28346a0d8d4d8b96d6c05fc39c34eec26e5c

Change-Id: Ic4fc01be7738fbabf8c7860dbe3476ab4caf5fc2

Change-Id: I4e5575f0d7ccfe2361b8cbf78e7dc079272c9f5f

Change-Id: Ib26fbfef3505299f754e5af6c437a85d7746fc28

Change-Id: I00512c6cef3a4af8df57c7263ceb853fb2db8140

Change-Id: I3b160e93d9319c8e1abda2a60f49f89c409d534b

Change-Id: If1ec3b64be327e8c48ec7efbacde208d2129fdb0

Change-Id: Iaa4880c8a207cfea509608e1ef4593794b6b31f2

Change-Id: I859719d41ced2e35d2765b636e627bb7edc3651e

Change-Id: I7c09f84b26eb499daafd1393b48f12abb8a6fb8f

Change-Id: I5cfc0aa9c436c7ba1b49337d06a0181f7cda920f

Change-Id: Ib093d2b9030006806ef9eba16c114f25a58e8f6b

Change-Id: I13738ef1f307cc5f563126bc7a92beaa01fde3bd

A bug was reported in Issue 702: "SIGILL (Illegal instruction) when
transcoding with vp9 - using FFmpeg". It was reproduced and fixed.

Change-Id: Ie32c149a89af02856084aeaf289e848a905c7700

Bitwise OR operation doesn't guarantee any subexpression evaluation order.
Just reading one bit now and ignoring the next one. For reference look at
vp9_decode_frame() implementation.

Change-Id: I4971686929838ae5ded8f43a38a2934db5e1d462

Change-Id: Ide9c408f4cee7408741ef8c0ffac01645a5a67ca

Change-Id: I69e868295b9798ba1599a411926de0891680032f

Added cast to int to silence MSVC warning.

Change-Id: I9ef4709d2e4cf0db070d9e52385c1b3f138b00a5