token: support iCombine ... gives

iris/base_logic/lib/token.v

@@ -49,6 +49,12 @@ Section lemmas.
     unseal. iIntros "Htok1 Htok2".
     iCombine "Htok1 Htok2" gives %[].
   Qed.
+  Global Instance token_combine_gives γ :
+    CombineSepGives (token γ) (token γ) ⌜False⌝.
+  Proof.
+    rewrite /CombineSepGives. iIntros "[H1 H2]".
+    iDestruct (token_exclusive with "H1 H2") as %[].
+  Qed.
 
 End lemmas.
 

iris_heap_lang/lib/spin_lock.v

@@ -34,7 +34,7 @@ Section proof.
   Local Definition locked (γ : gname) : iProp Σ := token γ.
 
   Local Lemma locked_exclusive (γ : gname) : locked γ -∗ locked γ -∗ False.
-  Proof. iIntros "H1 H2". by iDestruct (token_exclusive with "H1 H2") as %?. Qed.
+  Proof. iIntros "H1 H2". by iCombine "H1 H2" gives %?. Qed.
 
   (** The main proofs. *)
   Local Lemma is_lock_iff γ lk R1 R2 :