Address a comment.

Author: kazutakahirata

llvm/include/llvm/ProfileData/MemProf.h

@@ -416,10 +416,7 @@ struct IndexedMemProfRecord {
   // the last entry in the list with the same function GUID.
   llvm::SmallVector<CallStackId> CallSiteIds;
 
-  void clear() {
-    AllocSites.clear();
-    CallSiteIds.clear();
-  }
+  void clear() { *this = IndexedMemProfRecord(); }
 
   void merge(const IndexedMemProfRecord &Other) {
     // TODO: Filter out duplicates which may occur if multiple memprof