jitterbuffer: Add tracing of lock usage
jitterbuffer: Add tracing of lock usage

Helps with debugging lock usage

https://bugzilla.gnome.org/show_bug.cgi?id=762988

GrokImageCompression/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,stfl/gst-plugins-good,StreamUtils/gst-plugins-good,StreamUtils/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,StreamUtils/gst-plugins-good,GrokImageCompression/gst-plugins-good,GStreamer/gst-plugins-good,stfl/gst-plugins-good,GrokImageCompression/gst-plugins-good,hizukiayaka/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,stfl/gst-plugins-good,GrokImageCompression/gst-plugins-good,StreamUtils/gst-plugins-good,stfl/gst-plugins-good,GStreamer/gst-plugins-good,hizukiayaka/gst-plugins-good,hizukiayaka/gst-plugins-good,hizukiayaka/gst-plugins-good