qtdemux: Don't accumulate segment bases manually
qtdemux: Don't accumulate segment bases manually

gst_segment_do_seek() does that for us already, and doing it twice
will break non-flushing seeks in interesting ways. Leftover from 1.0
porting.

Also copy over segment offset and applied_rate, just in case.

StreamUtils/gst-plugins-good,GrokImageCompression/gst-plugins-good,hizukiayaka/gst-plugins-good,sebras/gst-plugins-good,chamois94/gst-plugins-good,Kurento/gst-plugins-good,froggatt/gst-plugins-good-m,Kurento/gst-plugins-good,ikonst/gst-plugins-good,shelsonjava/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,rawoul/gst-plugins-good,sebras/gst-plugins-good,vatavuserban/gst-plugins-good,ikonst/gst-plugins-good,hizukiayaka/gst-plugins-good,froggatt/gst-plugins-good-m,BigBrother-International/gst-plugins-good,BigBrother-International/gst-plugins-good,kittee/gst-plugins-good,sebras/gst-plugins-good,GStreamer/gst-plugins-good,froggatt/gst-plugins-good-m,hizukiayaka/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,ikonst/gst-plugins-good,GStreamer/gst-plugins-good,BigBrother-International/gst-plugins-good,Kurento/gst-plugins-good,kittee/gst-plugins-good,GStreamer/gst-plugins-good,rawoul/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,rawoul/gst-plugins-good,stfl/gst-plugins-good,vatavuserban/gst-plugins-good,GStreamer/gst-plugins-good,StreamUtils/gst-plugins-good,rawoul/gst-plugins-good,chamois94/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,vatavuserban/gst-plugins-good,stfl/gst-plugins-good,shelsonjava/gst-plugins-good,StreamUtils/gst-plugins-good,stfl/gst-plugins-good,vatavuserban/gst-plugins-good,GrokImageCompression/gst-plugins-good,shelsonjava/gst-plugins-good,sebras/gst-plugins-good,kittee/gst-plugins-good,kittee/gst-plugins-good,Kurento/gst-plugins-good,chamois94/gst-plugins-good,ikonst/gst-plugins-good,froggatt/gst-plugins-good-m,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,GrokImageCompression/gst-plugins-good,pexip/gst-plugins-good,hizukiayaka/gst-plugins-good,stfl/gst-plugins-good,StreamUtils/gst-plugins-good,pexip/gst-plugins-good,GrokImageCompression/gst-plugins-good,shelsonjava/gst-plugins-good,BigBrother-International/gst-plugins-good,Kurento/gst-plugins-good,chamois94/gst-plugins-good,pexip/gst-plugins-good