Use auto for iterator type

Author: romainbrenguier

src/goto-symex/goto_symex_state.cpp

@@ -470,8 +470,7 @@ bool goto_symex_statet::l2_thread_read_encoding(
     guardt write_guard;
     write_guard.add(false_exprt());
 
-    written_in_atomic_sectiont::const_iterator a_s_writes=
-      written_in_atomic_section.find(ssa_l1);
+    const auto a_s_writes = written_in_atomic_section.find(ssa_l1);
     if(a_s_writes!=written_in_atomic_section.end())
     {
       for(a_s_w_entryt::const_iterator it=a_s_writes->second.begin();