qtdemux: Don't override TIME segments from upstream that we just saw
qtdemux: Don't override TIME segments from upstream that we just saw

The point of d8fb7a9c96b108814beeaa0e63f818d4648c7fe9 was to not have any
spurious segments stored for later if we do BYTES->TIME conversion, but
overriding any TIME segments from upstream does not make any sense.

See https://bugzilla.gnome.org/show_bug.cgi?id=763165

https://bugzilla.gnome.org/show_bug.cgi?id=767071

Kurento/gst-plugins-good,Kurento/gst-plugins-good,Kurento/gst-plugins-good,Kurento/gst-plugins-good,Kurento/gst-plugins-good