Use entailment in `iEval` so that setoid rewriting works.

467b118b · Robbert Krebbers · e374f84c · 467b118b
Commit 467b118b authored Dec 31, 2017 by Robbert Krebbers
--- a/theories/proofmode/coq_tactics.v
+++ b/theories/proofmode/coq_tactics.v
@@ -414,9 +414,9 @@ Qed.

 (** * Basic rules *)
 Lemma tac_eval Δ Q Q' :
-  Q = Q' →
+  (Q' ⊢ Q) →
  envs_entails Δ Q' → envs_entails Δ Q.
-Proof. by intros ->. Qed.
+Proof. by intros <-. Qed.

 Lemma tac_assumption Δ i p P Q :
  envs_lookup i Δ = Some (p,P) → FromAssumption p P Q →