twacube: 'mark_t' is deprecated

* spot/mc/ec.hh, spot/mc/intersect.hh,
tests/core/twacube.cc: here.

spot/mc/ec.hh

 // -*- coding: utf-8 -*-
-// Copyright (C) 2015, 2016 Laboratoire de Recherche et
+// Copyright (C) 2015, 2016, 2018 Laboratoire de Recherche et
 // Developpement de l'Epita
 //
 // This file is part of Spot, a model checking library.
@@ -72,7 +72,7 @@ namespace spot
     bool push_state(product_state, unsigned dfsnum, acc_cond::mark_t cond)
     {
       uf_.makeset(dfsnum);
-      roots_.push_back({dfsnum, cond, 0U});
+      roots_.push_back({dfsnum, cond, {}});
       return true;
     }
 
@@ -146,7 +146,7 @@ namespace spot
       };
       std::queue<ctrx_element*> bfs;
 
-      acc_cond::mark_t acc = 0U;
+      acc_cond::mark_t acc = {};
 
       bfs.push(new ctrx_element({&this->todo.back().st, nullptr,
               this->sys_.succ(this->todo.back().st.st_kripke, this->tid_),

spot/mc/intersect.hh

@@ -89,7 +89,7 @@ namespace spot
     {
       self().setup();
       product_state initial = {sys_.initial(tid_), twa_->get_initial()};
-      if (SPOT_LIKELY(self().push_state(initial, dfs_number+1, 0U)))
+      if (SPOT_LIKELY(self().push_state(initial, dfs_number+1, {})))
         {
           todo.push_back({initial, sys_.succ(initial.st_kripke, tid_),
                 twa_->succ(initial.st_prop)});

tests/core/twacube.cc

@@ -39,12 +39,12 @@ int main()
   auto s1 = tg->new_state();
   auto s2 = tg->new_state();
   auto s3 = tg->new_state();
-  tg->new_edge(s1, s1, bddfalse, 0U);
-  tg->new_edge(s1, s2, p1, 0U);
+  tg->new_edge(s1, s1, bddfalse, {});
+  tg->new_edge(s1, s2, p1, {});
   tg->new_edge(s1, s3, p2, tg->acc().mark(1));
   tg->new_edge(s2, s3, p1 & p2, tg->acc().mark(0));
   tg->new_edge(s3, s1, p1 | p2, spot::acc_cond::mark_t({0, 1}));
-  tg->new_edge(s3, s2, p1 >> p2, 0U);
+  tg->new_edge(s3, s2, p1 >> p2, {});
   tg->new_edge(s3, s3, bddtrue, spot::acc_cond::mark_t({0, 1}));
 
   // Test translation