!3106 Optimization for map_data_.clear()

Merge pull request !3106 from Kang/optimization

mindspore/ccsrc/utils/ordered_map.h

@@ -88,7 +88,9 @@ class OrderedMap {
   }
 
   void clear() {
+    if (!map_data_.empty()) {
       map_data_.clear();
+    }
     sequential_data_.clear();
   }
 

mindspore/ccsrc/utils/ordered_set.h

@@ -127,7 +127,9 @@ class OrderedSet {
 
   // Clear the elements
   void clear() {
+    if (!mapped_data_.empty()) {
       mapped_data_.clear();
+    }
     ordered_data_.clear();
   }