Fix the superframe unit test for BIDIR_PRED

Change-Id: I2ef8e479893403581711abc020509c6863c2035d

test/superframe_test.cc

@@ -112,7 +112,13 @@ TEST_P(SuperframeTest, TestSuperframeIndexIsOptional) {
   ::libvpx_test::I420VideoSource video("hantro_collage_w352h288.yuv", 352, 288,
                                        30, 1, 0, 40);
   ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
+#if CONFIG_BIDIR_PRED
+  // NOTE: The use of BWDREF_FRAME will enable the coding of more non-show
+  //       frames besides ALTREF_FRAME.
+  EXPECT_GE(sf_count_, 1);
+#else
   EXPECT_EQ(sf_count_, 1);
+#endif  // CONFIG_BIDIR_PRED
 }
 
 VP9_INSTANTIATE_TEST_CASE(SuperframeTest, ::testing::Combine(