Fix a memory overflow issue in large scale tile use case

Increase the tok_count array size defined in VP9_COMP to avoid
out of boundary memory access.

Change-Id: Ib277c1102cb5f8355b1d69991532a94e24a2242e

vp9/encoder/vp9_encoder.h

@@ -268,7 +268,11 @@ typedef struct VP9_COMP {
 #endif  // CONFIG_LOOP_POSTFILTER
 
   TOKENEXTRA *tok;
+#if CONFIG_ROW_TILE
+  unsigned int tok_count[1024][1024];
+#else
   unsigned int tok_count[4][1 << 6];
+#endif
 
   // Ambient reconstruction err target for force key frames
   int ambient_err;