SRS supports including another configuration in the include package.
When generating configurations, we can only generate the changed
configurations, while the unchanged configurations are in the fixed
files, for example:
```nginx
listen 1935;
include server.conf;
```
In `server.conf`, we can manage the changing configurations with the
program:
```nginx
http_api { enabled on; }
```
However, during system initialization, we often create an empty
`server.conf`, and the content is generated only after the program
starts, so `server.conf` might be an empty file. This also makes it
convenient to use a script to confirm the existence of this file:
```bash
touch server.conf
```
Currently, SRS does not support empty configurations and will report an
error. This PR is to solve this problem, making it more convenient to
use include.
`TRANS_BY_GPT4`
---------
Co-authored-by: Haibo Chen <495810242@qq.com>
