qtdemux: Ignore raw audio streams when adjusting seek
Fixes #2711 (closed)
Raw audio streams' chunks are treated as keyframes, which becomes a problem when adjusting seeks - they can take priority over actual video keyframes, which shouldn't happen because those audio streams can be seeked freely. This patch simply ignores raw audio streams (indicated by str->subtype == FOURCC_soun && str->need_clip
), making sure they don't take priority anymore.