Change safestack reimplementation to match 0.9.8.

Fix additional gcc 4.2 value not used warnings.
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index bb07175..ccb30e0 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -764,7 +764,7 @@
 	if(x != NULL)
 		X509_free(x);
 	
-	sk_X509_NAME_set_cmp_func(stack,oldcmp);
+	(void)sk_X509_NAME_set_cmp_func(stack,oldcmp);
 
 	return ret;
 	}