Fix a bug in GetApproximateSizes

Summary: Need to pass through the memtable parameter.

Test Plan: built, tested through myrocks

Reviewers: igor, sdong, rven

Reviewed By: rven

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D49167

include/rocksdb/utilities/stackable_db.h

@@ -148,7 +148,8 @@ class StackableDB : public DB {
   virtual void GetApproximateSizes(ColumnFamilyHandle* column_family,
                                    const Range* r, int n, uint64_t* sizes,
                                    bool include_memtable = false) override {
-      return db_->GetApproximateSizes(column_family, r, n, sizes);
+    return db_->GetApproximateSizes(column_family, r, n, sizes,
+                                    include_memtable);
   }
 
   using DB::CompactRange;