Normally when we want a pointer to the end of a struct we just add 1 to
the struct pointer. However, when it is a zero-bit struct, the pointer
type being used during lowering is often a dummy pointer type that
actually points to a non-zero-bit type, so we actually want to add 0
instead, since a zero-bit struct begins and ends at the same address.
Jacob Young
0e3feebb04