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