Update packages

Here are commits to update systemd-selinux, openssh-selinux, sudo-selinux and utils-linux-selinux. Most changes follow upstream PKGBUILD, and I've also changed :
* .gitignore to ignore new downloaded files,
* "depends" definition of util-linux-selinux to force using coreutils-selinux,
* "makedepends" definition of openssh-selinux to no longer depend on linux-selinux-headers (because linux-headers now provides SELinux).

By the way, do you have any plan to remove linux-selinux package, now that the official linux package is compiled with SELinux?

Thanks