[Bug fortran/66605] -Wunused-parameter causes internal compiler error with gfortran 5.1.0

[kyle.niemeyer at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66605

--- Comment #1 from Kyle <kyle.niemeyer at gmail dot com> ---
I should note that removing "-Wunused-parameter" allows compilation without
error.