Function list_resize

Ensure ob_item has room for at least newsize elements, and set * ob_size to newsize. If newsize > ob_size on entry, the content * of the new slots at exit is undefined heap trash; it's the caller's * responsibility to overwrite them with sane values. * The number of allocated elements may grow, shrink, or stay the same. * Failure is impossible if newsize <= self.allocated on entry, although