Export avformat functions used in LAV
avformat: add a new flag to let the user indicate the file is on a slow network device
Export avcodec functions used in LAV
Silently error out when pos_limit exceeds pos_max instead of aborting the process.
HACK: disable mpegts crc checks for pat/pmt/...
Revert "mov: Set negative Sample_duration in STTS to 1"

This reverts commit 1892052f8dee858dcab3292d1c40c5deef67e18f.
Some files may violate the spec, but this way they play properly.
HACK: Add a function to manually add streams to the MPEG-TS demuxer

This is used by the BDMV demuxer when some streams are not detected by auto-probing
HACK: Don't return -1 in avformat_find_stream_info when codec details are still unknown.
mpegts: switch back to mpegts_get_pcr
lavfi: disable building of the lavfutils when not required
build: remove slashes from the last lines of x86 build files

This unbreaks compilation in mingw with CRLF line endings
lavfi: always link against avcodec

This is required because in recent changes the filter graph functions call avcodec functions.
Add Matroska demuxer based on Haalis MatroskaParser
mpegts: identify h264 mvc streams
file: increase io buffer for better performance on high latency resources
matroskadec_haali: Only accept a "sane" DefaultDuration for FPS.

Alot of files have their DefaultDuration set to an calculated
value which is not directly tied to the FPS, and because Matroska
actually doesn't specify the DefaultDuration to be tied to the FPS,
this is perfectly legal.

So, before assuming the DefaultDuration is the FPS, check if the value
actually makes sense. The most basic check here is that the FPS is
below 125fps, because any more really doesn't make sense.

If the FPS from the header is not set, avformat will probe the FPS
based on the files timestamps, which will give a much better result.
avr: take center_mix_level in account when mixing center to left/right
h264_parser: split sps extension and subset sps as well
mpegvideo: null out current_picture_ptr when allocation failed

This avoids using an uninitialized picture in further decode calls.
configure: don't use pkgconfig for libopus (HACK)