Set special flags and options for a response.
Calling this functions sets the given flags and options for the response.
which response should be modified;
flags to set for the response;
Additional arguments are a list of options (type-value pairs,
MHD_RO_END). It is mandatory to use
MHD_RO_END as last argument, even when there are no
MHD_NO on error,
MHD_YES on success.