Fix the FOREIGN-STRUCT-SLOT-SET compiler macro for aggregate slots.
Fix the FOREIGN-STRUCT-SLOT-SET compiler macro for aggregate slots.

Reported by Andy Hefner.

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