bench: Fix const-ness correctly
bench: Fix const-ness correctly

(Or at least as correctly as exec will let us.)

aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6