thread.c: drop WebPWorker prefix from static funcs

Change-Id: I7cd39c9e41bbf11157c488aff18631ef17fde464
thread.h: #ifdef when checking WEBP_USE_THREAD

prevents a warning with -Wundef and is consistent with thread.c

Change-Id: I60fa337c3b9daeea7302e86802402cb943cdb262
cosmetics: thread.c: drop a redundant comment

+ fix #if/#else/#endif comment

Change-Id: I76bfd3b123ed181897ed0feba721d5c1a3a2b0d7
Merge "cosmetics: thread.c: drop a redundant comment"
VP8EncIterator clean-up

- remove unused fields from iterator
- introduce VP8IteratorSetRow() too
- rename 'done_' to 'countdown_'
- bring y_left_/u_left_/v_left_ from VP8Encoder

Change-Id: Idc1c15743157936e4cbb7002ebb5cc3c90e7f92a
Merge "VP8EncIterator clean-up"
add WebPWorkerExecute() for convenient bypass

This is mainly for re-using the worker structs without using the
thread.

Change-Id: I8e1be29e53874ef425b15c192fb68036b4c0a359
Create LUT for PrefixEncode.

This speeds up lossless compression by 5%.
Change-Id: Ifd114b1d9850dc3aac74593809e7d48529d35e3d
bit_reader.h: cosmetics

- use const where applicable
- drop unnecessary string.h include

Change-Id: I560eef84fe17d3925768f6817c02ea79604c4379
slightly faster ParseIntraMode

+ cosmetics

Change-Id: Icb906d5f84f025ef9e04b71a73801a22cc990ee5
Merge "slightly faster ParseIntraMode"
Support for "Do not blend" in mux and demux libraries

Change-Id: I9566a8e2d059fe1ebd9ca99c7e13311bf3f8f281
Pack code & extra_bits to Struct (VP8LPrefixCode).

Also created variant VP8LPrefixEncodeBits that returns the
code & extra_bits only.
There's no impact on compression density and compression speed.

Change-Id: I2cafdd3438ac9270cd72ad9d57b383cdddfdfa4c
Merge "Support for "Do not blend" in mux and demux libraries"
Animated WebP: add "do no blend" option to spec

Marking certain frames as "do not blend" helps avoiding alpha-blending
at decode/render time.

It also helps inserting I-frames (frames which can be independently
decoded) into the animation.

Change-Id: Iaa222805db88d2f1c81104ce9d882e7c7ff8cfdb
Support for 'do not blend' option in vwebp

Change-Id: I563e192fa727816d11d8647c559ec407205ef40b
Merge "Support for 'do not blend' option in vwebp"
fix const-ness

Change-Id: I09c85fdb90b4380c8fc03c8b5652bb9cf29b2021
cosmetics

Change-Id: Ib6fa2a7e1db8c5c48607c7097520ffca34a6cb66
Merge "bit_reader.h: cosmetics"