fixed warning on zero-sized array in Z3_Backend
fixed warning on zero-sized array in Z3_Backend

finnhaedicke/metaSMT,hoangmle/metaSMT,finnhaedicke/metaSMT,finnhaedicke/metaSMT,nbruns1/metaSMT,nbruns1/metaSMT,agra-uni-bremen/metaSMT,agra-uni-bremen/metaSMT,nbruns1/metaSMT,hoangmle/metaSMT,agra-uni-bremen/metaSMT,hoangmle/metaSMT