When some of the parameters to standard C functions are known
constants, the compiler can optimize out the call to the actual
function.
When built with fortification enabled, the compiler previously
didn't actually end up calling the __<func>_chk functions in
most cases, as it could optimize out much of the calls. Now all
tested function calls should end up emitted as intended, making
this actually do functional testing of the __<func>_chk function
implementations.