Minor fix in vp9_encoder.h

Added the missing "int".

Change-Id: I7c8af3dee700837b40f010d53e1431a59370ae3a

vp9/encoder/vp9_encoder.h

@@ -390,7 +390,7 @@ typedef struct VP9_COMP {
   search_site_config ss_cfg;
 
   int mbmode_cost[INTRA_MODES];
-  unsigned inter_mode_cost[INTER_MODE_CONTEXTS][INTER_MODES];
+  unsigned int inter_mode_cost[INTER_MODE_CONTEXTS][INTER_MODES];
   int intra_uv_mode_cost[FRAME_TYPES][INTRA_MODES];
   int y_mode_costs[INTRA_MODES][INTRA_MODES][INTRA_MODES];
   int switchable_interp_costs[SWITCHABLE_FILTER_CONTEXTS][SWITCHABLE_FILTERS];