imgproc: dispatch color*

Lab/XYZ modes have been postponed (color_lab.cpp):
- need to split code for tables initialization and for pixels processing first
- no significant performance improvements for switching between SSE42 / AVX2 code generation

modules/imgproc/src/color.cpp

@@ -3,6 +3,7 @@
 // of this distribution and at http://opencv.org/license.html
 
 #include "precomp.hpp"
+#include "opencl_kernels_imgproc.hpp"
 #include "color.hpp"
 
 namespace cv