Function pxs_addfunc 

#[unsafe(no_mangle)]
pub extern "C" fn pxs_addfunc(
    module_ptr: *mut pxs_Module,
    name: *const c_char,
    func: pxs_Func,
    opaque: pxs_Opaque,
)

Add a callback to a module.

Pass in the modules pointer and callback paramaters.