Fix an issue with fzn2py.awk where no output variables are specified in the mzn model.
Fix an issue with fzn2py.awk where no output variables are specified in the mzn model.

eomahony/Numberjack,eomahony/Numberjack,JElchison/Numberjack,eomahony/Numberjack,eomahony/Numberjack,JElchison/Numberjack,JElchison/Numberjack,JElchison/Numberjack,JElchison/Numberjack,eomahony/Numberjack