Fix progma_once error

paddle/operators/elementwise_add_op.h

@@ -12,6 +12,8 @@
    See the License for the specific language governing permissions and
    limitations under the License. */
 
+#pragma once
+
 #include "paddle/operators/elementwise_op.h"
 
 namespace paddle {

paddle/operators/elementwise_div_op.h

@@ -12,6 +12,8 @@
    See the License for the specific language governing permissions and
    limitations under the License. */
 
+#pragma once
+
 #include "paddle/operators/elementwise_op.h"
 
 namespace paddle {

paddle/operators/elementwise_sub_op.h

@@ -12,6 +12,7 @@
    See the License for the specific language governing permissions and
    limitations under the License. */
 
+#pragma once
 #include "paddle/operators/elementwise_op.h"
 
 namespace paddle {