bugfix: fixed compilation error with nginx 1.7.5+ because nginx 1.7.5+ changes the API in the events subsystem.

Author: agentzh

src/ngx_postgres_upstream.c

@@ -561,11 +561,19 @@ ngx_postgres_upstream_free_connection(ngx_log_t *log, ngx_connection_t *c,
             }
         }
 
+#if defined(nginx_version) && nginx_version >= 1007005
+        if (rev->posted) {
+#else
         if (rev->prev) {
+#endif
             ngx_delete_posted_event(rev);
         }
 
+#if defined(nginx_version) && nginx_version >= 1007005
+        if (wev->posted) {
+#else
         if (wev->prev) {
+#endif
             ngx_delete_posted_event(wev);
         }