Function pxs_object_callrt 

#[unsafe(no_mangle)]
pub extern "C" fn pxs_object_callrt(
    runtime: pxs_Runtime,
    var: *mut pxs_Var,
    method: *const c_char,
    args: *mut pxs_Var,
) -> *mut pxs_Var

Call a function on a object, and use a Enum for runtime rather than a var.

var is self.