Use () for all_traits.

compiler/rustc_middle/src/query/mod.rs

@@ -1420,7 +1420,7 @@ rustc_queries! {
     /// A vector of every trait accessible in the whole crate
     /// (i.e., including those from subcrates). This is used only for
     /// error reporting.
-    query all_traits(_: CrateNum) -> &'tcx [DefId] {
+    query all_traits(_: ()) -> &'tcx [DefId] {
         desc { "fetching all foreign and local traits" }
     }