Follow-up to r1891477.

Axe a few lines of code and document a potential optimization

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1891591 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/modules/proxy/proxy_util.c b/modules/proxy/proxy_util.c
index f6bab19..03b6d84 100644
--- a/modules/proxy/proxy_util.c
+++ b/modules/proxy/proxy_util.c
@@ -3677,17 +3677,15 @@
         }
         if (!found) {
             proxy_worker **runtime;
+            /* XXX: a thread mutex is maybe enough here */
             apr_global_mutex_lock(proxy_mutex);
             runtime = apr_array_push(b->workers);
-            *runtime = apr_palloc(conf->pool, sizeof(proxy_worker));
+            *runtime = apr_pcalloc(conf->pool, sizeof(proxy_worker));
             apr_global_mutex_unlock(proxy_mutex);
-            memset(*runtime, 0, sizeof(proxy_worker));
             (*runtime)->hash = shm->hash;
             (*runtime)->balancer = b;
             (*runtime)->s = shm;
-#if APR_HAS_THREADS
-            (*runtime)->tmutex = NULL;
-#endif
+
             rv = ap_proxy_initialize_worker(*runtime, s, conf->pool);
             if (rv != APR_SUCCESS) {
                 ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(00966) "Cannot init worker");