Dear All,

the attached patch fixes a dependency check in frontend optimzation
for nested implied-do IO.  The problem appeared for >= 3 loops only
as the check considered dependencies to be only of band form instead
of triangular form.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

As this fixes a regression since 8-release, I plan to backport
to all active branches.

Thanks,
Harald