Log Message:
ffmpeg3: updated to 3.4.4

version 3.4.4:
- avcodec/dvdsub_parser: Allocate input padding
- avcodec/dvdsub_parser: Init output buf/size
- avcodec/dirac_dwt_template: Fix signedness regression in interleave()
- avformat/movenc: Write version 2 of audio atom if channels is not known
- swresample/arm: rename labels to fix xcode build error
- avcodec/imgconvert: fix possible null pointer dereference