Fix compiler warning on get_tx_scale for new_quant

Change-Id: I568365060848dc9e2171becaef4928ff430dc622
diff --git a/av1/encoder/quantize.c b/av1/encoder/quantize.c
index 07270d1..644a4c3 100644
--- a/av1/encoder/quantize.c
+++ b/av1/encoder/quantize.c
@@ -15,6 +15,7 @@
 #include "aom_mem/aom_mem.h"
 #include "aom_ports/mem.h"
 
+#include "av1/common/idct.h"
 #include "av1/common/quant_common.h"
 #include "av1/common/scan.h"
 #include "av1/common/seg_common.h"