test: fix compiation warning
test: fix compiation warning

-Wunused-function would kick in because of the close_loop function,
but there tests and benchmarks which actually don't use any loop.

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso