[Bug sanitizer/65769] [UBSAN] qt-4.6 and qt-4.7 applications using qobject_cast may crash

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65769

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note GCC will optimize the object call into a __builtin_trap now too.