Realip: fixed duplicate processing on redirects (ticket #1098). Duplicate processing was possible if the address set by realip was listed in set_realip_from, and there was an internal redirect so module context was cleared. This resulted in exactly the same address being set, so this wasn't a problem before the $realip_remote_addr variable was introduced, though now results in incorrect $realip_remote_addr being picked. Fix is to use ngx_http_realip_get_module_ctx() to look up module context even if it was cleared. Additionally, the order of checks was switched to check the configuration first as it looks more effective.