Add 'const' to static tables to fix some warnings

Change-Id: I8604a1f644302f5e6249b89c96550e1d5715188f
warning: assignment from incompatible pointer type

av1/common/txb_common.h

diff --git a/av1/common/txb_common.h b/av1/common/txb_common.h
index 9ec2ab8..5c3132f 100644
--- a/av1/common/txb_common.h
+++ b/av1/common/txb_common.h
@@ -320,15 +320,15 @@
 
 #define SIG_REF_OFFSET_NUM 7
 #if CONFIG_EOB_FIRST
-static int sig_ref_offset[SIG_REF_OFFSET_NUM][2] = {
+static const int sig_ref_offset[SIG_REF_OFFSET_NUM][2] = {
   { 2, 1 }, { 2, 0 }, { 1, 2 }, { 1, 1 }, { 1, 0 }, { 0, 2 }, { 0, 1 },
 };
 
-static int sig_ref_offset_vert[SIG_REF_OFFSET_NUM][2] = {
+static const int sig_ref_offset_vert[SIG_REF_OFFSET_NUM][2] = {
   { 2, 1 }, { 2, 0 }, { 3, 0 }, { 1, 1 }, { 1, 0 }, { 4, 0 }, { 0, 1 },
 };
 
-static int sig_ref_offset_horiz[SIG_REF_OFFSET_NUM][2] = {
+static const int sig_ref_offset_horiz[SIG_REF_OFFSET_NUM][2] = {
   { 0, 3 }, { 0, 4 }, { 1, 2 }, { 1, 1 }, { 1, 0 }, { 0, 2 }, { 0, 1 },
 };
 
@@ -358,7 +358,7 @@
   return count;
 }
 #else
-static int sig_ref_offset[SIG_REF_OFFSET_NUM][2] = {
+static const int sig_ref_offset[SIG_REF_OFFSET_NUM][2] = {
   { -2, -1 }, { -2, 0 }, { -1, -2 }, { -1, -1 },
   { -1, 0 },  { 0, -2 }, { 0, -1 },
 };
@@ -704,7 +704,7 @@
 }
 
 #define MAX_POS_CTX 8
-static int pos_ctx[MAX_HVTX_SIZE] = {
+static const int pos_ctx[MAX_HVTX_SIZE] = {
   0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5,
   6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7,
 };

av1/encoder/encodetxb.c

diff --git a/av1/encoder/encodetxb.c b/av1/encoder/encodetxb.c
index aad2038..8175fa3 100644
--- a/av1/encoder/encodetxb.c
+++ b/av1/encoder/encodetxb.c
@@ -1513,11 +1513,11 @@
 
 #if FAST_OPTIMIZE_TXB
 #define ALNB_REF_OFFSET_NUM 2
-static int alnb_ref_offset[ALNB_REF_OFFSET_NUM][2] = {
+static const int alnb_ref_offset[ALNB_REF_OFFSET_NUM][2] = {
   { -1, 0 }, { 0, -1 },
 };
 #define NB_REF_OFFSET_NUM 4
-static int nb_ref_offset[NB_REF_OFFSET_NUM][2] = {
+static const int nb_ref_offset[NB_REF_OFFSET_NUM][2] = {
   { -1, 0 }, { 0, -1 }, { 1, 0 }, { 0, 1 },
 };
 #endif  // FAST_OPTIMIZE_TXB
@@ -1553,7 +1553,7 @@
   const int col = coeff_idx - (row << txb_info->bwl);
   if (check_nz_neighbor(qc)) {
 #if FAST_OPTIMIZE_TXB
-    int(*ref_offset)[2];
+    const int(*ref_offset)[2];
     int ref_num;
     if (fast_mode) {
       ref_offset = alnb_ref_offset;
@@ -1563,7 +1563,7 @@
       ref_num = SIG_REF_OFFSET_NUM;
     }
 #else
-    int(*ref_offset)[2] = sig_ref_offset;
+    const int(*ref_offset)[2] = sig_ref_offset;
     const int ref_num = SIG_REF_OFFSET_NUM;
 #endif
     for (int i = 0; i < ref_num; ++i) {
@@ -1589,7 +1589,7 @@
 
   if (check_base_neighbor(qc)) {
 #if FAST_OPTIMIZE_TXB
-    int(*ref_offset)[2];
+    const int(*ref_offset)[2];
     int ref_num;
     if (fast_mode) {
       ref_offset = nb_ref_offset;
@@ -1625,7 +1625,7 @@
 
   if (check_br_neighbor(qc)) {
 #if FAST_OPTIMIZE_TXB
-    int(*ref_offset)[2];
+    const int(*ref_offset)[2];
     int ref_num;
     if (fast_mode) {
       ref_offset = nb_ref_offset;
@@ -1934,7 +1934,7 @@
 
 #if TEST_OPTIMIZE_TXB
 #define ALL_REF_OFFSET_NUM 17
-static int all_ref_offset[ALL_REF_OFFSET_NUM][2] = {
+static const int all_ref_offset[ALL_REF_OFFSET_NUM][2] = {
   { 0, 0 },  { -2, -1 }, { -2, 0 }, { -2, 1 }, { -1, -2 }, { -1, -1 },
   { -1, 0 }, { -1, 1 },  { 0, -2 }, { 0, -1 }, { 1, -2 },  { 1, -1 },
   { 1, 0 },  { 2, 0 },   { 0, 1 },  { 0, 2 },  { 1, 1 },