rollback: undo this commit "test (kqueue)connection completely in ngx_http_upstream_test_connect()"

Undo commit 422086fb7df6daef082fcaf7459b9ce72f84eaf4.

Maxim Dounin's reply for this patch is as following:

On Fri, Aug 16, 2013 at 10:19:00AM +0800, Xiaochen Wang wrote:
> Without this patch, nginx can work well because c->recv() will return
> NGX_ERROR when read event timedout expires.

Note well that the purpose of ngx_http_upstream_test_connect()
call before writing to an upstream is to properly report source of
the error if it happens.  It's bad idea to do getsockopt() in all
cases for performance reasons
Merge pull request #373 from chobits/kqueue_bugfix_rollback

rollback: undo this commit "test (kqueue)connection completely in ngx_ht...