gstreamer/libs/base: initial commit of GstBaseIdleSrc

A new src that spawns a single thread when it needs to push something,
and then joins said thread and goes back to an idle state, not consuming
system resources.

Co-authored-by: Camilo Celis Guzman <[email protected]>

Author: havardgraff

subprojects/gstreamer/libs/gst/base/base.h

@@ -29,6 +29,7 @@
 #include <gst/base/gstbaseparse.h>
 #include <gst/base/gstbasesink.h>
 #include <gst/base/gstbasesrc.h>
+#include <gst/base/gstbaseidlesrc.h>
 #include <gst/base/gstbasetransform.h>
 #include <gst/base/gstbitreader.h>
 #include <gst/base/gstbitwriter.h>