Remove bin/arch-linux-grsec

This script is now managed in another git repository:
https://github.com/fishilico/shared/tree/master/archlinux-seckernel

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
.shell/aliases: add diff-patch alias

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>