Adjust a module visibility.

Author: nnethercote

compiler/rustc_middle/src/dep_graph/mod.rs

@@ -17,7 +17,7 @@ use crate::ty::print::with_reduced_queries;
 use crate::ty::{self, TyCtxt};
 
 mod debug;
-pub mod dep_node;
+pub(crate) mod dep_node;
 mod dep_node_key;
 mod edges;
 mod graph;