Restore vp10_default_scan_orders[]

vp10_default_scan_orders was removed in:
e5848dea Rectangular transforms 4x8 & 8x4
This fixes compiler error in vp10_quantize_test.cc
Change-Id: I1b8a637e011f9426c3b41e61e00e3babc80defba

vp10/common/scan.c

@@ -3111,6 +3111,13 @@ DECLARE_ALIGNED(16, static const int16_t, vp10_qtr_iscan_32x32[1024]) = {
 };
 #endif  // CONFIG_EXT_TX
 
+const scan_order vp10_default_scan_orders[TX_SIZES] = {
+  {default_scan_4x4,   vp10_default_iscan_4x4,   default_scan_4x4_neighbors},
+  {default_scan_8x8,   vp10_default_iscan_8x8,   default_scan_8x8_neighbors},
+  {default_scan_16x16, vp10_default_iscan_16x16, default_scan_16x16_neighbors},
+  {default_scan_32x32, vp10_default_iscan_32x32, default_scan_32x32_neighbors},
+};
+
 #if CONFIG_EXT_TX
 const scan_order vp10_intra_scan_orders[TX_SIZES][TX_TYPES] = {
   {  // TX_4X4

vp10/common/scan.h

@@ -29,6 +29,7 @@ typedef struct {
   const int16_t *neighbors;
 } scan_order;
 
+extern const scan_order vp10_default_scan_orders[TX_SIZES];
 extern const scan_order vp10_intra_scan_orders[TX_SIZES][TX_TYPES];
 
 static INLINE int get_coef_context(const int16_t *neighbors,