(This commit also modifies the deps/media-playback, obs-ffmpeg, and
win-dshow modules)
More fixes due to ffmpeg renaming some constants and deprecating
AVFMT_RAWPICTURE and AV_PIX_FMT_VDA_VLD.
Latter replaced by AV_PIX_FMT_VIDEOTOOLBOX per ffmpeg dev advice.
Closesjp9000/obs-studio#1061
On windows, if you were saving a file name or directory with characters
that are not of the current windows character set, it could cause the
file saving process to fail. This fixes it so that on windows it uses
wmain and converts the unicode command line to a UTF-8 command line,
which works with FFmpeg.