dnsapi: add DnsGetCacheDataTable stub

[Hans Leidekker]

On Thu, 2016-05-19 at 23:27 -0500, Austin English wrote: 
> +typedef int (*DNS_GET_CACHE_DATA_TABLE)(PDNSCACHEENTRY);

You don't need this.

> +DNS_GET_CACHE_DATA_TABLE WINAPI DnsGetCacheDataTable( DNSCACHEENTRY *cache )
> +{
> +    FIXME( "(%p) stub\n", cache);
> +    return ERROR_SUCCESS;
> +}

It should probably return DNS_STATUS and the parameter might actually be
DNSCACHEENTRY **. Some tests would be helpful here.