dct16x16_test: quiet unused-function warning

in non-x86 builds

Change-Id: I1171e9c7e7ea5bcdea70bf5e3d28b07d6bb5578f

test/dct16x16_test.cc

@@ -293,6 +293,7 @@ void iht16x16_12(const tran_low_t *in, uint8_t *out, int stride, int tx_type) {
   vp9_highbd_iht16x16_256_add_c(in, out, stride, tx_type, 12);
 }
 
+#if HAVE_SSE2
 void idct16x16_10_add_10_c(const tran_low_t *in, uint8_t *out, int stride) {
   vpx_highbd_idct16x16_10_add_c(in, out, stride, 10);
 }
@@ -301,7 +302,6 @@ void idct16x16_10_add_12_c(const tran_low_t *in, uint8_t *out, int stride) {
   vpx_highbd_idct16x16_10_add_c(in, out, stride, 12);
 }
 
-#if HAVE_SSE2
 void idct16x16_256_add_10_sse2(const tran_low_t *in, uint8_t *out, int stride) {
   vpx_highbd_idct16x16_256_add_sse2(in, out, stride, 10);
 }