Add 8x8 fDCT unit test.

Also factorize ACMRandom to acm_random.h.

Change-Id: I3b6eeb36fcbf7ae6dd3d2892bc40348f5c17982b

test/test.mk

diff --git a/test/test.mk b/test/test.mk
index a9ccaf2..601050e 100644
--- a/test/test.mk
+++ b/test/test.mk
@@ -1,6 +1,8 @@
 LIBVPX_TEST_SRCS-yes += test.mk
+LIBVPX_TEST_SRCS-yes += acm_random.h
 LIBVPX_TEST_SRCS-yes += boolcoder_test.cc
 LIBVPX_TEST_SRCS-yes += fdct4x4_test.cc
+LIBVPX_TEST_SRCS-yes += fdct8x8_test.cc
 LIBVPX_TEST_SRCS-yes += test_libvpx.cc
 
 LIBVPX_TEST_DATA-yes += hantro_collage_w352h288.yuv