Add WORKERS_COUNT option for pkg-repo.
Add some debug messages to `pkg-repo`.
Fix distributing tasks over workers.
Fix disambiguity with POLL_IN and POLLIN.
Do not hard fail if we can update any of repos.
Improve errors reporting when updating multirepo.
Fix upgrade SQL.

Pointy hat to:	bapt
Reported by:	az
Print repository in search.

Issue:	#871
Reported by:	@kpaasial
Ignore meta.txz file when building repo.