Fixed a build issue

Adding the missed include file.

Change-Id: I7e48df6b0633afbebaf1ccb3062ae404e7203dc9

vp9/common/vp9_postproc.h

@@ -13,6 +13,7 @@
 #define VP9_COMMON_VP9_POSTPROC_H_
 
 #include "vpx_ports/mem.h"
+#include "vpx_scale/yv12config.h"
 #include "vp9/common/vp9_ppflags.h"
 
 #ifdef __cplusplus