Saving individual dives should not change the exiting filename

The current data file is not the same as the file to which individual
dives were saved.

Reported-by: Jan Schubert <Jan.Schubert@GMX.li>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

divelist.c

@@ -1637,7 +1637,6 @@ static void save_as_cb(GtkWidget *menuitem, struct dive *dive)
 	gtk_widget_destroy(dialog);
 
 	if (filename){
-		set_filename(filename, TRUE);
 		save_dives_logic(filename, TRUE);
 		g_free(filename);
 	}