ext_tile: add 2 tile encoding modes

Added 2 tile encoding modes:
TILE_NORMAL mode supports the large-scale tile coding up to 1024 x 1024
tiles;
TILE_VR mode supports the large-scale tile coding and also the decoding
of a single tile.

TILE_NORMAL mode allows the non-vr content to be encoded in multiple tiles
without using the coding tool that are designed for vr applications.

Change-Id: Id804806a1bbcb916b7f5dc7e2c5509d88f3defcb
diff --git a/av1/common/onyxc_int.h b/av1/common/onyxc_int.h
index 6c28678..5fc92f0 100644
--- a/av1/common/onyxc_int.h
+++ b/av1/common/onyxc_int.h
@@ -356,6 +356,9 @@
 #endif  // !CONFIG_EXT_TILE
   int tile_cols, tile_rows;
   int tile_width, tile_height;  // In MI units
+#if CONFIG_EXT_TILE
+  unsigned int tile_encoding_mode;
+#endif  // CONFIG_EXT_TILE
 
 #if CONFIG_DEPENDENT_HORZTILES
   int dependent_horz_tiles;