klibc.inc: add mapping for 64-bit ARM builds

Klibc is following the kernel naming ('arm64') instead of the toolchain naming ('aarch64').

Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
klibc: upgrade from 2.0.2 to release 2.0.3

Klibc now supports aarch64 / arm64
While there, remove PR/INC_PR from the recipes

Signed-off-by: Andrea Adami <andrea.adami@gmail.com>