- Determine sizing and alignments of pointers to types as
distinct from the size and alignment of the types themselves.
- Declare all buffer pointers in the MSL device address space.
- Support struct pointer recursion, where structs can
contain pointers to themselves or to a parent struct.
- Add SPIRType::was_forward_referenced to track if a type was forward
referenced, to help emit MSL structs in the correct dependency order.
- Handle pointers to pointers that are not just arrays of arrays.
