Break down a D type into basic (register) types for the 32-bit x86 ABI.
This breaks a type down into 'simpler' types that can be passed to a function in registers, and returned in registers. This is the implementation for the 32-bit x86 ABI.
type to break down
tuple of types, each element can be passed in a register. A tuple of zero length means the type cannot be passed/returned in registers.