recorder: remove warnings

Replace deprecation attributes with a commented note to remove 30 or so
compilation warnings.

Deprecation should be used to tell clients what they should and
shouldn't use, and since these fields are private, only the
MediaRecorder can use them.

Change-Id: I227d3508f982b174ca71efca49d5fedad47b1888

src/media/media_recorder.h

@@ -100,9 +100,8 @@ class MediaRecorder {
 
         std::string path_;
 
-        [[deprecated]]
+        // NOTE do not use dir_ or filename_, use path_ instead
         std::string dir_;
-        [[deprecated]]
         std::string filename_;
 
         unsigned nbExpectedStreams_ = 0;