arm32: implement AAPCS32 homogeneous float aggregates incl unions,
arm32: fix reversed arguments in the small-struct return coercion,abi test: __aeabi_uldivmod so the arm32 corpus links
i386: treat a bit_field as the aggregate it is in C, fixing a segfault on return,
abi test: document the i386 microarch baseline; do not read a signal exit as a type index