no_fork : Remove allocation for empty vector (#3544)

* no_fork : Remove allication for empty vector

* style

src/ngraph/op/constant.hpp

@@ -95,7 +95,8 @@ namespace ngraph
                     ", expected ",
                     shape_size(m_shape),
                     ".");
-
+                if (values.size())
+                {
                     if (type.is_integral())
                     {
                         if (type.is_signed())
@@ -126,6 +127,7 @@ namespace ngraph
                         }
                         write_values(dvalues);
                     }
+                }
                 constructor_validate_and_infer_types();
             }