Add a conditional compilation macro to VP8 unit test.

In many tests in VP8, the denoiser is disabled. By adding this
conditional comilation macro, the unit test will not be included
when denoiser is not enabled.

Change-Id: I6edec85c996acca22aacd11161c52408be2660a3
diff --git a/test/datarate_test.cc b/test/datarate_test.cc
index 5c2cad8..1b7863a 100644
--- a/test/datarate_test.cc
+++ b/test/datarate_test.cc
@@ -126,6 +126,7 @@
   int denoiser_on_;
 };
 
+#if CONFIG_TEMPORAL_DENOISING
 // Check basic datarate targeting, for a single bitrate, but loop over the
 // various denoiser settings.
 TEST_P(DatarateTestLarge, DenoiserLevels) {
@@ -154,6 +155,7 @@
         << " The datarate for the file missed the target!";
   }
 }
+#endif  // CONFIG_TEMPORAL_DENOISING
 
 TEST_P(DatarateTestLarge, BasicBufferModel) {
   denoiser_on_ = 0;
@@ -647,7 +649,7 @@
   ASSERT_LE(effective_datarate_[0], cfg_.rc_target_bitrate * 1.15)
       << " The datarate for the file is greater than target by too much!";
 }
-#endif
+#endif  // CONFIG_VP9_TEMPORAL_DENOISING
 
 VP8_INSTANTIATE_TEST_CASE(DatarateTestLarge, ALL_TEST_MODES);
 VP9_INSTANTIATE_TEST_CASE(DatarateTestVP9Large,