sctpclientsink: Protect critical regions
sctpclientsink: Protect critical regions

Change-Id: Idab0c8535242fdf25fb69b6c5bde41234b18a762

KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins