Sets the parent_refcount field of #GstCapsFeatures. This field is used to
determine whether a caps features is mutable or not. This function should only be
called by code implementing parent objects of #GstCapsFeatures, as described in
the MT Refcounting section of the design documents.
Sets the parent_refcount field of #GstCapsFeatures. This field is used to determine whether a caps features is mutable or not. This function should only be called by code implementing parent objects of #GstCapsFeatures, as described in the MT Refcounting section of the design documents.