Update information forCVE-2018-6930/imagemagick

The use of the problematic buffer and CreateOpenCLBuffer has been
introduced later in the ImageMagick-7 development around 7.0.2. Exact
version not pin-pointed but likely when refactoring in

https://github.com/ImageMagick/ImageMagick/commit/66acef5cd2089f66bbdb7dc7b3b18e2eb6d792ae

the following changed:

	@@ -4359,8 +4392,8 @@ static Image *ComputeResizeImage(const Image* image,MagickCLEnv clEnv,
	   resizeFilterCoefficient=GetResizeFilterCoefficient(resizeFilter);
	   for (i = 0; i < 7; i++)
	     coefficientBuffer[i]=(float) resizeFilterCoefficient[i];
	-  cubicCoefficientsBuffer=CreateOpenCLBuffer(device,CL_MEM_READ_ONLY |
	-    CL_MEM_COPY_HOST_PTR,7*sizeof(float),&coefficientBuffer);
	+  cubicCoefficientsBuffer=CreateOpenCLBuffer(device,CL_MEM_COPY_HOST_PTR |
	+    CL_MEM_READ_ONLY,7*sizeof(*resizeFilterCoefficient),&coefficientBuffer);
	   if (cubicCoefficientsBuffer == (cl_mem) NULL)
	   {
	     (void) OpenCLThrowMagickException(device,exception,GetMagickModule(),