rtspsrc: Always interrupt CMD_LOOP after new command
Normally, the loop function gets interrupted when a new command is received by the calling of gst_rtspsrc_connection_flush. However, this only works if currently busy receiving, otherwise the command thread would get stuck in gst_rtspsrc_loop. With this patch, the function gst_rtspsrc_loop checks if pending_cmd has been set to a new command before receiving, forcing the function to interrupt if this is the case.
Fixes #598 (closed)