tests: silence a few type related warnings

Change-Id: If908328c1dbbb5bd84c57e30fab1cda1804933e4
diff --git a/test/ivf_video_source.h b/test/ivf_video_source.h
index 88bc597..926f801 100644
--- a/test/ivf_video_source.h
+++ b/test/ivf_video_source.h
@@ -47,7 +47,8 @@
   virtual void Init() {
     // Allocate a buffer for read in the compressed video frame.
     compressed_frame_buf_ = new uint8_t[libvpx_test::kCodeBufferSize];
-    ASSERT_TRUE(compressed_frame_buf_) << "Allocate frame buffer failed";
+    ASSERT_TRUE(compressed_frame_buf_ != NULL)
+        << "Allocate frame buffer failed";
   }
 
   virtual void Begin() {