Implicit port read buffer completion.

To disable implicit completion, handler should reset msg->buf field.

src/nxt_master_process.c

@@ -141,8 +141,6 @@ nxt_port_master_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     b = msg->buf;
 
     nxt_debug(task, "master data: %*s", b->mem.free - b->mem.pos, b->mem.pos);
-
-    b->mem.pos = b->mem.free;
 }
 
 
@@ -175,7 +173,6 @@ nxt_port_master_start_worker_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     start += app_conf.name.length + 1;
 
     conf = nxt_conf_json_parse(mp, start, b->mem.free);
-    b->mem.pos = b->mem.free;
 
     if (conf == NULL) {
         nxt_log(task, NXT_LOG_CRIT, "configuration parsing error");