[klibc] syscalls: Add syscalls needed by arm64

arm64 uses generic syscalls, and does not include the "noat",
"noflags", and "deprecated" syscalls.

This patch adds substitution functions for system calls not available
on arm64.

Originally-by: Neil Williams <codehelp@debian.org>
Originally-by: Anil Singhar <anil.singhar@linaro.org>
Signed-off-by: Steve Capper <steve.capper@linaro.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
22 files changed