Adds a function to the function filter registry.
Use a static instance of this class to add a function's name to the function filter registry CXllFunctionFilter. The constructor calls CXllFunctionFilter::Publish(fnName, true). This means that the function will be included in the list of functions published under an opt-in policy, i.e. when all functions are suppressed except those listed in the registry.
The class has no effect under an opt-out policy.
Instances of this class are automatically generated by the FunctionFilterOptOut function extension.