report correct interval amplification

Summary: as title

Test Plan: make release

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19515

db/internal_stats.cc

@@ -294,9 +294,9 @@ bool InternalStats::GetProperty(DBPropertyType property_type,
       snprintf(
           buf, sizeof(buf),
           "Amplification interval: %.1f write, %.1f compaction\n",
-          (double)(interval_bytes_written + wal_bytes) /
+          (double)(interval_bytes_written + interval_wal_bytes) /
               (interval_bytes_new + 1),
-          (double)(interval_bytes_written + interval_bytes_read + wal_bytes) /
+          (double)(interval_bytes_written + interval_bytes_read + interval_wal_bytes) /
               (interval_bytes_new + 1));
       value->append(buf);