Function soup_sys::soup_session_prefetch_dns

pub unsafe extern "C" fn soup_session_prefetch_dns(
    session: *mut SoupSession, 
    hostname: *const c_char, 
    cancellable: *mut GCancellable, 
    callback: SoupAddressCallback, 
    user_data: gpointer
)

This is supported on crate feature v2_38 only.