Prefer use logging in butil or glog?

**Is your feature request related to a problem? (你需要的功能是否与某个问题有关?)**
I see there is a simple logging mechanism delivered along with brpc in butil/logging.cc. I'm not sure whether it is aimed to be production ready or just a default demo. It lack some important feature, like rotation. But on the other hand, i see @chenBright is still try to optimize it for performance month ago.

**Describe the solution you'd like (描述你期望的解决方法)**
I want to know, whether a logging implementation is in brpc's road map, or we just depend on glog's ecosystem？

**Describe alternatives you've considered (描述你想到的折衷方案)**

**Additional context/screenshots (更多上下文/截图)**

Start by reading butil/logging.cc and reviewing the current logging behavior, including the missing rotation support and recent performance work mentioned in the issue. Compare that implementation with the project’s use of glog, then document whether brpc should improve butil logging or rely on glog and what roadmap decision follows.

Written by the indexing model from the issue text.