add vp8 variance test

Change-Id: I4e94ee2c4e2360d6a11a454c323f2899c1bb6f72
diff --git a/test/test.mk b/test/test.mk
index e7a1dcd..e0e6d1e 100644
--- a/test/test.mk
+++ b/test/test.mk
@@ -50,6 +50,7 @@
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += set_roi.cc
 LIBVPX_TEST_SRCS-yes                   += sixtap_predict_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += subtract_test.cc
+LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += variance_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += vp8_fdct4x4_test.cc
 
 endif # VP8