Change incr comp test when adding explicit Sized bound

Given the previous change to add implicit `Sized` bounds only if there
isn't already an explicit `Sized` bound, now the incr comp machinery
doesn't consider adding the explicit bound as being dirty, as long as
`-Zincremental-ignore-spans` is set.

Author: estebank

tests/incremental/hashes/trait_defs.rs

@@ -559,10 +559,10 @@ trait TraitAddBuiltinBoundToMethodTypeParameter {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5")]
+#[rustc_clean(except="hir_owner_nodes", cfg="cfail5")]
 #[rustc_clean(cfg="cfail6")]
 trait TraitAddBuiltinBoundToMethodTypeParameter {
-    #[rustc_clean(except="hir_owner_nodes,predicates_of", cfg="cfail2")]
+    #[rustc_clean(except="hir_owner_nodes", cfg="cfail2")]
     #[rustc_clean(cfg="cfail3")]
     #[rustc_clean(except="hir_owner_nodes,predicates_of", cfg="cfail5")]
     #[rustc_clean(cfg="cfail6")]