add cmath header for bfloat (#31792)

chenwhql · web-flow · commit 3f66e7deab7c · 2021-03-23T19:55:16.000+08:00
diff --git a/paddle/fluid/platform/bfloat16.h b/paddle/fluid/platform/bfloat16.h
@@ -16,6 +16,7 @@
 
 #include <stdint.h>
 
+#include <cmath>
 #include <cstring>
 #include <iostream>
 #include <limits>
