- Handle strings that have an opening but no closing quote

fixes the endless loop reported in

Bug: 10521

- Fix a typo.
Change-Id: I17b4a15e780d1d6122841a308348518063f82a59
Reviewed-on: https://code.wireshark.org/review/4467
Reviewed-by: Anders Broman <a.broman58@gmail.com>