[Bug c/108518] Format-overflow warning using `*.s` directive with null but zero-length string

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108518

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
In similar fashion memcpy/memset with a size argument of 0 passed, they have to
be a non-null pointer.