Upstream: fixed running posted requests (ticket #788). Previously, the upstream resolve handler always called ngx_http_run_posted_requests() to run posted requests after processing the resolver response. However, if the handler was called directly from the ngx_resolve_name() function (for example, if the resolver response was cached), running posted requests from the handler could lead to the following errors: - If the request was scheduled for termination, it could actually be terminated in the resolve handler. Upper stack frames could reference the freed request object in this case. - If a significant number of requests were posted, and for each of them the resolve handler was called directly from the ngx_resolve_name() function, posted requests could be run recursively and lead to stack overflow. Now ngx_http_run_posted_requests() is only called from asynchronously invoked resolve handlers.