Set #DIV/0! error in VAR() OpenCL implementation when appropriate

Returning DBL_MAX doesn't make sense. The traditional C++ implementation and
other spreadsheet products return an error.

Change-Id: I8189c3ecf4aa7b1df00ec2fd8b91030085848bf4

sc/source/core/opencl/op_statistical.cxx

@@ -194,7 +194,7 @@ void OpVar::GenSlidingWindowFunction(std::stringstream &ss,
         }
     }
     ss << "    if (fCount <= 1.0)\n";
-    ss << "        return DBL_MAX;\n";
+    ss << "        return CreateDoubleError(errDivisionByZero);\n";
     ss << "    else\n";
     ss << "        return vSum * pow(fCount - 1.0,-1.0);\n";
     ss << "}\n";