demux: remove experimental FRGM parsing

references to fragments remain, along with some superfluous checks; these
will be removed in a future commit.

Change-Id: I39fe9314900ecbc5d60e5065b65fa1b4c668af63
webp-container-spec: remove references to fragments

this portion of the format was never finalized

Change-Id: I80aa1b27457a0e52b047c7284df2f58b181ca5d8
dec_neon: add DC8uv

~87% faster.

Change-Id: I73fe77437792f1361ce8ab0b411132c6ec0fa021
dec_neon: add DC8uvNoTop / DC8uvNoLeft

adds do_top/do_left flags to DC8uv; ~88% / ~92% faster respectively
no change in DC8uv speed.

Change-Id: I109ec4d9ad13c9db64516e98ed4693a21a3e9b54
Merge changes I109ec4d9,I73fe7743

* changes:
  dec_neon: add DC8uvNoTop / DC8uvNoLeft
  dec_neon: add DC8uv
Merge "demux: remove experimental FRGM parsing"
Merge "webp-container-spec: remove references to fragments"
demux: restore strict fragment flag check

inadvertently removed in:
demux: remove experimental FRGM parsing

Change-Id: Ia9bb8211e2153df51e7a01cabe8552524b8ed218