lang:xyz filtering on shard level

[Han-Wen Nienhuys]

sym:repo lang:Go

yields 0 results, because "Go" is not a recognizd language. However, we do get trigrams for "repo", and the query takes a couple of seconds with cold caches.

We could do a bitmask union of all the languages in a repo, and check that before starting iteration.

this is a win, because many repos have just a few languages.