ARC: libc/sysdeps: add __kernel_long and __kernel_ulong

Linux 3.4 added these two types and updated various exported header
files to use them. While other architectures were updated before,
this was not the case for ARC.

This fixes the build failure with Linux 3.10 headers.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>