mdssvc: better support for search with mdfind from Macs
When searching Samba via Spotlight from a Mac with mdfind, only 50 results are returned.
It seems the changes for bug #15342 where one step in the right direction. There, a status indicator meaning "search is still being processed" was implemented, returning a special status indicator (0x23) in a response, when the query was still running in the backend, eg Elasticsearch, and we haven't got any result when when the Mac already comes along asking for results of a query.
Turns out, we should also return 0x23, ie "search is still being processed" when we have some initial search results from the backend. Otherwise mdfind will stop querying for more results. It works in Finder, as the Finder by default employs a "live" search where it just keeps polling for more results even after the server returned an empty result set. The Finder just keeps on querying in some interval, typically 4 seconds, and a Mac server Spotlight server might return new results if new files where created that match the query, hence "live" search.