[Bug tree-optimization/126975] __bos/__bdos(&p->inner, 1) collapses into type 0 when subobject inner ends in a FAM

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126975

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
The inner flex array may not extend beyond the outer object size (it might
cover tail padding that's eventually there).  I'd expect &p->inner to be of
size 8.