[Bug c++/57622] -W -Wall -Werror -Wno-unused gives Wunused-parameter warning

[lucier at math dot purdue.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57622

--- Comment #2 from lucier at math dot purdue.edu ---
This was fixed by the patch for PR61106 and backported to 4.8 and 4.9, so it
should be closed as FIXED.