Preprocessor: fix possible bug in histval (need to limit search of aux vars to...

Preprocessor: fix possible bug in histval (need to limit search of aux vars to aux vars for lagged vars, otherwise we could have a wrong match with some other kind)

SymbolTable.cc

@@ -371,7 +371,8 @@ int
 SymbolTable::searchAuxiliaryVars(int orig_symb_id, int orig_lead_lag) const
 {
   for (int i=0; i < aux_vars.size();++i)
-    if ((aux_vars[i].get_orig_symb_id() == orig_symb_id) && (aux_vars[i].get_orig_lead_lag() == orig_lead_lag))
+    if ((aux_vars[i].get_type() == avEndoLag || aux_vars[i].get_type() == avExoLag)
+        && aux_vars[i].get_orig_symb_id() == orig_symb_id && aux_vars[i].get_orig_lead_lag() == orig_lead_lag)
       return aux_vars[i].get_symb_id();
   return -1;
 }