[Bug fortran/91424] Extend warnings about DO loops

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91424
Bug 91424 depends on bug 91422, which changed state.

Bug 91422 Summary: Illegal Fortran in 
testsuite/libgomp.oacc-fortran/routine-7.f90
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91422

           What    |Removed                     |Added
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             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED