Enable test system to detect transforms misusing 'stride' parameter

This would have caught the bug introduced in patch set 1 of
https://chromium-review.googlesource.com/#/c/397378/

Change-Id: I9c6d5d9c4c98aed5ac48c4fb1c4ff4131b0df1d5
diff --git a/test/av1_fht4x4_test.cc b/test/av1_fht4x4_test.cc
index 104b865..075646c 100644
--- a/test/av1_fht4x4_test.cc
+++ b/test/av1_fht4x4_test.cc
@@ -59,6 +59,7 @@
     inv_txfm_ = GET_PARAM(1);
     tx_type_ = GET_PARAM(2);
     pitch_ = 4;
+    height_ = 4;
     fwd_txfm_ref = fht4x4_ref;
     bit_depth_ = GET_PARAM(3);
     mask_ = (1 << bit_depth_) - 1;