Attempt #2 at fixing Windows test errors in snapshot dataset.

PiperOrigin-RevId: 253701905

Author: Frank Chen

tensorflow/core/kernels/data/experimental/snapshot_dataset_op.cc

@@ -48,7 +48,7 @@ namespace {
 enum SnapshotMode { READER = 0, WRITER = 1, PASSTHROUGH = 2 };
 
 // Defaults to 10 GiB per shard.
-const int64 kDefaultShardSizeBytes = 10L * 1024 * 1024 * 1024;
+const int64 kDefaultShardSizeBytes = 10LL * 1024 * 1024 * 1024;
 
 const size_t kHeaderSize = sizeof(uint64);