fix gcc53 on cpu vec (#13020)

tensor-tang · qingqing01 · commit d941192e747e · 2018-08-29T09:52:02.000+08:00
diff --git a/paddle/fluid/operators/math/cpu_vec.h b/paddle/fluid/operators/math/cpu_vec.h
@@ -14,6 +14,7 @@ limitations under the License. */
 
 #pragma once
 #include <cmath>
+#include <functional>
 #include <string>
 #include "paddle/fluid/platform/cpu_info.h"
 #ifdef __AVX__
