Pulling latest libwebm from upstream.

Change-Id: I62edafb0b0283160c9b4060fd5907e3aad6c7820

Change-Id: If8044d9c71afe02ed1e6c94487344e143bdfcd74

Change-Id: Ieb9b455b8aaef9884391021b7f640ef24c554687

Change-Id: I512f2a287dd8765879a2d1144e2f028dc65f71ff

Change-Id: I0816ec12ec0a6f21d0f25f10c214b5fd327afc6c

Copy up to a certain bsize, otherwise set to a fixed bsize.
This helsp to reduce artifact near moving boundary caused by full partition
copy without checking motion of super-block.
This artifact can occur at speeds 3,4 in real-time mode.
Issue: https://code.google.com/p/webm/issues/detail?id=738.

Change-Id: I05812521fd38816a467f72eb6a951cae4c227931

Change-Id: I5a65d6fdb27516aefda0473ac45b05186cf0913c

Change-Id: Iab3effc39064f265426c82b455ef38d37dcce5a8

Commit introduced the leak: "Removing XMA legacy from VP9 code."
I5e9dfc50b6312848df8c3b8276f6b4d0c7ff9cf9

Change-Id: Ia1f91bb8403bef340de9f089fa78b3fccc3e9917

Change-Id: I7b2b690d2d51d55daa642be4131e5febd78cbe0a

Change-Id: Ic68caec1bcb8a88f443c3e40ce9770eade5bd320

Change-Id: Ib4e31ba74c4b882bd93942ef743f4a189892738d

These functions do nothing about rate control.

Change-Id: I714e80b1c1f4f9aa157a56df705247fce6db138d

ARF overlays now use the same rate correction factor as regular inter
frames, further testing would be needed to see if it makes sense to use
a completely separate rate correction factor for ARF overlays.

$ vpxenc --cpu-used=5  --fps=50/1 --target-bitrate=2000
         parkjoy.y4m -o out.webm
=> Before: 3356 kb/s
=> After: 2271 kb/s

Change-Id: I73e4defa615ba7a8a2bdb845864f4b1721cbbffe

Change-Id: If1b0a2d6603ce24f5dd99855e8dfe459e7a2835a

Change-Id: Ib3886cb7cafc211581f4f9e7f76782d9d1984434

This commit estimates the motion vector rate cost right after full
pixel motion search. It combines this and the mode cost and compares
the corresponding rate-distortion cost. If it is already above the
current best one, skip the rest sub-pixel motion search and modeling
process. For pedestrian_area 1080p at 4000 kpbs, the speed -5 runtime
goes down from 39425 ms -> 38399 ms.

Change-Id: If4cd7119fd6c266798d5cf1d19d19ab425e52a26

Change-Id: I4685706b816dd1c45500e1387c9f63edb2fa1962