整理命名空间 (#1409)

* 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>

src/Record/MP4.h

@@ -24,8 +24,6 @@
 #include "mov-buffer.h"
 #include "mov-format.h"
 
-using namespace std;
-
 namespace mediakit {
 
 //mp4文件IO的抽象接口类
@@ -124,7 +122,7 @@ public:
     /**
      * 获取并清空文件缓存
      */
-    string getAndClearMemory();
+    std::string getAndClearMemory();
 
 protected:
     uint64_t onTell() override;
@@ -134,7 +132,7 @@ protected:
 
 private:
     uint64_t _offset = 0;
-    string _memory;
+    std::string _memory;
 };
 
 }//namespace mediakit