adec: skip flac headers
adec: skip flac headers

GStreamer's flacparse always pushes as normal buffers, and newer libav
versions don't like that.

Signed-off-by: Felipe Contreras <de77a8b9cd239b204c19c52ed62e48ab47243362@gmail.com>

felipec/gst-av,felipec/gst-av,felipec/gst-av