Add a hacky remidy for #6038

The proper fix I think is:

* move rust-lang/rust library crates to a separate workspace
* when packaging rust-src component, vendor sources of external deps

crates/project_model/src/lib.rs

@@ -485,6 +485,11 @@ impl ProjectWorkspace {
                 }
             }
         }
+        if crate_graph.patch_cfg_if() {
+            log::debug!("Patched std to depend on cfg-if")
+        } else {
+            log::debug!("Did not patch std to depend on cfg-if")
+        }
         crate_graph
     }
 }