Fix build error for Cycles standalone

This does not affect the Blender release.

Ref D7915

intern/cycles/app/cycles_standalone.cpp

@@ -26,6 +26,7 @@
 #include "util/util_args.h"
 #include "util/util_foreach.h"
 #include "util/util_function.h"
+#include "util/util_image.h"
 #include "util/util_logging.h"
 #include "util/util_path.h"
 #include "util/util_progress.h"