Auto merge of #85337 - cjgillot:less-anon, r=michaelwoerister

Avoid creating anonymous nodes with zero or one dependency.

Anonymous nodes are only useful to encode dependencies, and cannot be replayed from one compilation session to another.
As such, anonymous nodes without dependency are always green.
Anonymous nodes with only one dependency are equivalent to this dependency.

cc #45408
cc `@michaelwoerister`

compiler/rustc_incremental/src/persist/save.rs

@@ -229,6 +229,7 @@ pub fn build_dep_graph(
     }
 
     Some(DepGraph::new(
+        &sess.prof,
         prev_graph,
         prev_work_products,
         encoder,