Find the ParamSpec with the given name for an interface.
Generally, the interface vtable passed in as g_iface
will be the default vtable from
default_interface_ref, or, if you know the interface has already been
loaded, default_interface_peek.
g_iface |
any interface vtable for the interface, or the default vtable for the interface |
property_name |
name of a property to look up. |
the ParamSpec for the property of the interface with the name |