Fix scope to contain an set of if conditions

Author: thomasspriggs

src/goto-programs/scope_tree.h

@@ -14,6 +14,8 @@
 
 #include <goto-programs/goto_program.h>
 
+#include <unordered_set>
+
 class code_frontend_declt;
 
 typedef std::size_t node_indext;
@@ -95,8 +97,7 @@ class scope_treet
   struct declaration_statet
   {
     goto_programt::targett instruction;
-    optionalt<irep_idt> label;
-    std::unordered_map<irep_idt, irep_id_hash> if_conditions_added;
+    std::unordered_set<irep_idt, irep_id_hash> if_conditions_added;
   };
 
   scope_treet()