[Patch, fortran] PR20880 - Failure to detect procedures encompassing own interface

[François-Xavier Coudert]

> With
>    make check-gfortran RUNTESTFLAGS="dg.exp=func_derived_3.f90 -de"
> I can reproduce this as often as I want. But if I run manually
>    gfortran -O0 func_derived_3.f90
> or copy even the complete command from dbg.log, it does not give an ICE.

Try adding -pedantic?

FX