* feat: remove using namespace mediakit in header files.
(cherry picked from commit d44aeb339a8a0e1f0455be82b21fe4b1b536299f)
* feat: remove using namespace mediakit in FFmpegSource.h
* feat: remove using namespace mediakit in RtpExt.h
* feat: remove using namespace mediakit in header files.
* feat: remove using namespace std in header files.
* feat: remove using namespace std in header files when zltoolkit remove std in header
* 补充命名空间
* 整理命名空间
* 整理命名空间2
* 修复macos ci
* 修复编译问题
* 修复编译问题2
* 修复编译问题3
Co-authored-by: Johnny <hellojinqiang@gmail.com>
Co-authored-by: Xiaofeng Wang <wasphin@gmail.com>
https://www.viva64.com/en/w/v828/
编译器会对返回本地变量优化([Named] Return Value Optimization (RVO/NRVO)),
无论是 C++11 之前还是之后, 添加 move 后反而会影响该优化.
C++ Core Guidelines F.48: Do not return std::move(local)