Remove libvpx from FFmpeg in favour of ffvp8.

ffmpeg/source/config/Chrome/linux/x64/config.asm

Index: ffmpeg/source/config/Chrome/linux/x64/config.asm
diff --git a/ffmpeg/source/config/Chrome/linux/x64/config.asm b/ffmpeg/source/config/Chrome/linux/x64/config.asm
index 557eb87a458aa250e03ab5da35aab198fdd63bda..83bcb1f101849e9a6265721f89bce5171f79fec2 100644
--- a/ffmpeg/source/config/Chrome/linux/x64/config.asm
+++ b/ffmpeg/source/config/Chrome/linux/x64/config.asm
@@ -67,7 +67,6 @@
 %define CONFIG_BSFS
 %define CONFIG_DECODERS
 %define CONFIG_DEMUXERS
-%define CONFIG_ENCODERS
 %define CONFIG_PARSERS
 %define CONFIG_PROTOCOLS
 %define CONFIG_AVCODEC
@@ -81,7 +80,6 @@
 %define CONFIG_GOLOMB
 %define CONFIG_H264DSP
 %define CONFIG_H264PRED
-%define CONFIG_LIBVPX
 %define CONFIG_MDCT
 %define CONFIG_MPEGAUDIODSP
 %define CONFIG_PIC
@@ -94,15 +92,15 @@
 %define CONFIG_H264_DECODER
 %define CONFIG_THEORA_DECODER
 %define CONFIG_VP3_DECODER
+%define CONFIG_VP8_DECODER
 %define CONFIG_AAC_DECODER
 %define CONFIG_MP3_DECODER
 %define CONFIG_VORBIS_DECODER
 %define CONFIG_PCM_F32LE_DECODER
 %define CONFIG_PCM_S16LE_DECODER
 %define CONFIG_PCM_U8_DECODER
-%define CONFIG_LIBVPX_DECODER
-%define CONFIG_LIBVPX_ENCODER
 %define CONFIG_MPEGAUDIO_PARSER
+%define CONFIG_VP8_PARSER
 %define CONFIG_H264_MP4TOANNEXB_BSF
 %define CONFIG_MATROSKA_DEMUXER
 %define CONFIG_MOV_DEMUXER