Fix compiler warnigns for msvc2013

Change-Id: I1e32bf8f6872a6fb7e9cabe86483e94805e2f790

vp9/encoder/vp9_encodemb.c

@@ -93,7 +93,7 @@ typedef struct vp9_token_state {
   int           rate;
   int           error;
   int           next;
-  signed char   token;
+  int16_t       token;
   short         qc;
 } vp9_token_state;
 

vp9/encoder/vp9_tokenize.h

@@ -65,7 +65,7 @@ extern const int16_t vp9_cat6_low_cost[256];
 extern const int16_t vp9_cat6_high_cost[128];
 extern const int16_t vp9_cat6_high10_high_cost[512];
 extern const int16_t vp9_cat6_high12_high_cost[2048];
-static INLINE int16_t vp9_get_cost(uint8_t token, EXTRABIT extrabits,
+static INLINE int16_t vp9_get_cost(int16_t token, EXTRABIT extrabits,
                                    const int16_t *cat6_high_table) {
   if (token != CATEGORY6_TOKEN)
     return vp9_extra_bits[token].cost[extrabits];