Cycles: Fix long compile time with MSVC.

Compile time per kernel increased alot after recent image commits, re-shuffle some code to fix this.

Patch by "LazyDodo".

Differential Revision: https://developer.blender.org/D2012

intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h

@@ -24,6 +24,7 @@
 #include "kernel_math.h"
 #include "kernel_types.h"
 #include "kernel_globals.h"
+#include "kernel_cpu_image.h"
 #include "kernel_film.h"
 #include "kernel_path.h"
 #include "kernel_path_branched.h"