[Bug target/69789] g++ -O2 is removing tests against a variable that can be changed

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69789

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This works in GCC 6 on aarch64 as far as I can tell.