Function boring_sys::SSL_CTX_set_tlsext_servername_callback

pub unsafe extern "C" fn SSL_CTX_set_tlsext_servername_callback(
    ctx: *mut SSL_CTX, 
    cb: Option<extern "C" fn(s: *mut SSL, out_alert: *mut c_int, arg: *mut c_void) -> c_int>
) -> c_int