frame.c: Copy the whole subclass in ast_frdup().

The problem is ast_frdup() does not copy whole frame.subclass for voice,
video and image frames, only the format is copied.  For video frames, the
subclass structure contains the .frame_ending flag used to put the RTP
marker where it needs to be.

ASTERISK-25894 #close

Change-Id: I812ca90e84ed5d4f473b997d0dd0d3c5a915fe33

main/frame.c

@@ -320,11 +320,10 @@ struct ast_frame *ast_frdup(const struct ast_frame *f)
 	}
 
 	out->frametype = f->frametype;
+	out->subclass = f->subclass;
 	if ((f->frametype == AST_FRAME_VOICE) || (f->frametype == AST_FRAME_VIDEO) ||
 		(f->frametype == AST_FRAME_IMAGE)) {
-		out->subclass.format = ao2_bump(f->subclass.format);
-	} else {
-		memcpy(&out->subclass, &f->subclass, sizeof(out->subclass));
+		ao2_bump(out->subclass.format);
 	}
 	out->datalen = f->datalen;
 	out->samples = f->samples;