[Bug fortran/57160] short-circuit IF only with -ffrontend-optimize

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57160

--- Comment #11 from janus at gcc dot gnu.org ---
Patch posted at: https://gcc.gnu.org/ml/fortran/2018-07/msg00086.html