Use cf_update_capture_comment() to save the capture comment (instead of

Use cf_update_capture_comment() to save the capture comment (instead of
summary_update_comment() which is no longer necessary).
cf_update_capture_comment() has the advantage that it doesn't mark the file
as unsaved unless the comment actually changed.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@42832 f5534014-38df-0310-8fa8-9805f1628bb7