Now that userspace is making use of kernel-provided sanitized headers for
working out supported interfaces, we need to be a bit more diligent with
matching the syscall definitions with their actual wiring/support state.

In theory it shouldn't hurt anything since sys_ni_syscall will ultimately
do the right thing, but there's also not much need to lie about legacy
x86 syscalls that we've never supported.

This tightens things up a bit for uClibc at least.
Suggested-by: NCarmelo Amoroso <carmelo.amoroso@st.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>