Move the registration of callback functions to special functions
designed for that.  This removes the potential error to mix data and
function pointers.

Please note that I'm a little unsure how incorrect calls to the old
ctrl functions should be handled, in som cases.  I currently return 0
and that's it, but it may be more correct to generate a genuine error
in those cases.
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 531969b..ca6c03d 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -101,6 +101,9 @@
 	ssl_bad_method,
 	tls1_default_timeout,
 	&TLSv1_enc_data,
+	ssl_undefined_function,
+	ssl3_callback_ctrl,
+	ssl3_ctx_callback_ctrl,
 	};
 
 static long tls1_default_timeout(void)
@@ -138,4 +141,9 @@
 	{
 	return(0);
 	}
+
+long tls1_callback_ctrl(SSL *s, int cmd, void *(*fp)())
+	{
+	return(0);
+	}
 #endif