multiqueue: do not reset last push result when pushing events
multiqueue: do not reset last push result when pushing events

Use the last result as a default when pushing a item from a single queue,
otherwise the status gets reset to _OK when pushing events.

This causes problems when mistakenly activating a not-linked stream
that is being ignored upstream as it is not being used (adaptive
scenarios), it will make the multiqueue post a buffering message
on a pad that won't receive buffers

https://bugzilla.gnome.org/show_bug.cgi?id=725917

Lachann/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,centricular/gstreamer,cfoch/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,jpakkane/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,centricular/gstreamer,jpxiong/gstreamer,cablelabs/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,cfoch/gstreamer,cablelabs/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,cablelabs/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,centricular/gstreamer,krichter722/gstreamer,mparis/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,cfoch/gstreamer,cfoch/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,Lachann/gstreamer,mparis/gstreamer,jpakkane/gstreamer,jpxiong/gstreamer,cfoch/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,Lachann/gstreamer