[Bug fortran/64973] Duplicate use-statements could be diagnosed

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64973

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Correct link: https://gcc.gnu.org/ml/fortran/2015-02/msg00036.html.