try to eliminate failure in opencv_imgproc_test

modules/imgproc/src/color.cpp

@@ -2695,7 +2695,7 @@ static bool ocl_cvtColor( InputArray _src, OutputArray _dst, int code, int dcn )
     UMat src = _src.getUMat(), dst;
     Size sz = src.size(), dstSz = sz;
     int scn = src.channels(), depth = src.depth(), bidx;
-    int dims = 2, stripeSize = 32;
+    int dims = 2, stripeSize = 1;
     size_t globalsize[] = { src.cols, src.rows };
     ocl::Kernel k;
 

modules/imgproc/src/opencl/cvtcolor.cl

@@ -109,7 +109,7 @@ __kernel void RGB2Gray(__global const uchar* srcptr, int srcstep, int srcoffset,
                        __global uchar* dstptr, int dststep, int dstoffset,
                        int rows, int cols)
 {
-#if 0
+#if 1
     const int x = get_global_id(0);
     const int y = get_global_id(1);