bump Iris; fix for std++ change

opam

@@ -9,6 +9,6 @@ build: [make "-j%{jobs}%"]
 install: [make "install"]
 remove: ["rm" "-rf" "%{lib}%/coq/user-contrib/iris_examples"]
 depends: [
-  "coq-iris" { (= "dev.2018-05-17.0.463474fb") | (= "dev") }
+  "coq-iris" { (= "dev.2018-06-23.0.a6e581d0") | (= "dev") }
   "coq-autosubst" { = "dev.coq86" }
 ]

theories/concurrent_stacks/concurrent_stack4.v

@@ -268,13 +268,11 @@ Section stack_works.
           iDestruct "Hstack" as (l'' v' xs) "[% [Hl'' [Hstack HP]]]".
           iDestruct ("Hmove" with "HP") as "Hmove".
           iDestruct (fupd_mask_mono with "Hmove") as "Hmove";
-            last iMod "Hmove" as "[HP HQ'']".
-          { apply ndisj_subseteq_difference; try solve_ndisj. }
+            last iMod "Hmove" as "[HP HQ'']"; first solve_ndisj.
           iDestruct "Hcont" as "[Hsucc _]".
           iDestruct ("Hsucc" with "HP") as "Hsucc".
           iDestruct (fupd_mask_mono with "Hsucc") as "Hsucc";
-            last (iMod "Hsucc" as "[HQ HP]").
-          { apply ndisj_subseteq_difference; try solve_ndisj. }
+            last (iMod "Hsucc" as "[HQ HP]"); first solve_ndisj.
           iMod ("Hclose2" with "[Hl'' Hstack HP]").
           { iExists l'', v', xs; iSplit; iFrame; auto. }
           iModIntro.