debug: Fix clang open fortify wrapper (BZ 31927)

The fcntl.h fortify wrapper for clang added by 86889e22
missed the __fortify_clang_overload_arg and and also added the
mode argument for the __fortify_function_error_function function,
which leads clang to be able to correct resolve which overloaded
function it should emit.

Checked on x86_64-linux-gnu.

Reported-by: Khem Raj <raj.khem@gmail.com>
Tested-by: Khem Raj <raj.khem@gmail.com>