message: Fix crash when same function name has different return type
diff: @@ -1212,6 +1212,7 @@ StateValue FnCall::toSMT(State &s) const {
  unpack_inputs(s, arg->getType(), s[*arg], inputs, ptr_inputs);
  fnName_mangled << "#" << arg->getType().toString();
  }
  + fnName_mangled << '!' << getType();
  if (!isVoid())
  unpack_ret_ty(out_types, getType());
  