mediahandler: forward-declare AVFrame

Change-Id: I8c27143000c8e02d2245e0329ad87f5cf846a73f

src/plugin/mediahandler.h

@@ -22,11 +22,15 @@
 
 #include "streamdata.h"
 #include "observer.h"
-#include <libavutil/frame.h>
+
 #include <string>
 #include <memory>
 #include <map>
 
+extern "C" {
+struct AVFrame;
+}
+
 namespace jami {
 
 using avSubjectPtr = std::shared_ptr<Observable<AVFrame*>>;