r2580, r2585, r2586, r2587, r2591, r2626 merge:

try_files

ignore EINVAL from setsockopt() on Solaris

test wildcard tail hash existance

fix /?new=arg?old=arg redirect case

avoid a double redirect response if
*) a request is going in a keep alive state,
*) the request body should be discarded,
*) epoll/rtsig reports about the response header has been sent,
*) and write event handler calls core phase handler

fix fastcgi_store

proxy/fastcgi_store did not delete incomplete files

skip protected symlinks in autoindex

allow POST without Content-Length

if_modified_since