Prefer "goto cleanup" over "do {... if (error) break; ... } while(0)"

construction for error handling/jump (as suggested by Ruediger).

Hence we can move backend->close = 1 (for mod_proxy_wstunnel) and
proxy_run_detach_backend() (for mod_proxy_http2) in the cleanup fallback.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1729749 13f79535-47bb-0310-9956-ffa450edef68