Cherry-pick-29260, change import math.h to cmath (#29260) (#31212)

pangyoki · web-flow · commit 84a5ed9f49be · 2021-02-26T18:08:29.000+08:00
ATT，cherry pick PR #29260
diff --git a/paddle/fluid/memory/allocation/best_fit_allocator.cc b/paddle/fluid/memory/allocation/best_fit_allocator.cc
@@ -13,7 +13,7 @@
 // limitations under the License.
 
 #include "paddle/fluid/memory/allocation/best_fit_allocator.h"
-#include <math.h>
+#include <cmath>
 
 namespace paddle {
 namespace memory {
