This commit modifies the interleave calculation to allow growing when incoming data is before the segment start. The rationale is that there is no requirement whatsoever for data before the segment start to be "coherent" on all streams. For example, a demuxer could rightfully send data from the video stream from the previous keyframe (potentially quite a bit before the segment start) and the audio from just before the segment start. This will activate the same logic as growing the interleave when some streams haven't received buffers yet. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1892>