Events: handle only active events in eventport.

We generate both read and write events if an error event was returned by
port_getn() without POLLIN/POLLOUT, but we should not try to handle inactive
events, they may even have no handler.


git-svn-id: svn://svn.nginx.org/nginx/trunk@5172 73f98a42-aea0-e011-b76d-00259023448c
Events: fixed typos in two previous commits.


git-svn-id: svn://svn.nginx.org/nginx/trunk@5173 73f98a42-aea0-e011-b76d-00259023448c
Upstream: warn if multiple non-stackable balancers are installed.


git-svn-id: svn://svn.nginx.org/nginx/trunk@5174 73f98a42-aea0-e011-b76d-00259023448c