[prange] Do not assume all pointers are the same size [PR115009]

[prange] Do not assume all pointers are the same size [PR115009]

In a world with same sized pointers we can always reuse the storage
slots, but since this is not always the case, we need to be more
careful.  However, we can always store an undefined, because that
requires no extra storage.

gcc/ChangeLog:

	PR tree-optimization/115009
	* value-range-storage.cc (prange_storage::alloc): Do not assume
	all pointers are the same size.
	(prange_storage::prange_storage): Same.
	(prange_storage::fits_p): Same.