Revert "remove li_let_bind for wand"

This reverts commit 6e03a868.

theories/typing/automation.v

@@ -99,8 +99,8 @@ Ltac liRIntroduceLetInGoal :=
   lazymatch goal with
   | |- @envs_entails ?PROP ?Δ ?P =>
     lazymatch P with
-    (* | @bi_wand ?PROP ?Q ?T => *)
-      (* li_let_bind T (fun H => constr:(@envs_entails PROP Δ (@bi_wand PROP Q H))) *)
+    | @bi_wand ?PROP ?Q ?T =>
+      li_let_bind T (fun H => constr:(@envs_entails PROP Δ (@bi_wand PROP Q H)))
     | @typed_val_expr ?Σ ?tG ?e ?T =>
       li_let_bind T (fun H => constr:(@envs_entails PROP Δ (@typed_val_expr Σ tG e H)))
     | @typed_write ?Σ ?tG ?b ?e ?ot ?v ?ty ?Mov ?T =>