add :size option to defcunion as with defcstruct
add :size option to defcunion as with defcstruct

dochang/cffi,dkochmanski/cffi,stassats/cffi,attila-lendvai/cffi,mcna/cffi,stassats/cffi,dkochmanski/cffi,cffi/cffi,kingcheez/cffi-cheez,wesen/cffi,marsijanin/cffi,wesen/cffi,cffi/cffi,akovalenko/cffi,dkochmanski/cffi,dochang/cffi,stassats/cffi,dochang/cffi,akovalenko/cffi,cffi/cffi,marsijanin/cffi,3b/cffi,3b/cffi,wesen/cffi,mcna/cffi,marsijanin/cffi,attila-lendvai/cffi,3b/cffi,akovalenko/cffi,kingcheez/cffi-cheez,kingcheez/cffi-cheez