remove double negation in comment

src/librustc_trans/collector.rs

@@ -706,9 +706,9 @@ fn is_drop_in_place_intrinsic<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 fn can_have_local_instance<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                      def_id: DefId)
                                      -> bool {
-    // Take a look if we have the definition available. If not, we
-    // will not emit code for this item in the local crate, and thus
-    // don't create a translation item for it.
+    // Take a look if we have the definition available. If so, we
+    // will emit code for this item in the local crate, and thus
+    // create a translation item for it.
     def_id.is_local() || tcx.sess.cstore.is_item_mir_available(def_id)
 }