Arch: Add/fix 'checkupdates' utility from 'pacman-contrib'.

[cvlc12]

This allows checking for updates safely with $ checkupdates in order to decide on whether it's time to build a new image..

[cvlc12]

Fixed architecture which supports auto and added dependency

Arch Linux 6.17.9-arch1-1 (hvc0)

Try contacting this VM's SSH server via 'ssh vsock%3634382124' from host.

archlinux login: particleos (automatic login)

Password: ****

[particleos@archlinux ~]$ checkupdates 
bash 5.3.3-2 -> 5.3.8-1
ca-certificates-mozilla 3.118.1-1 -> 3.119-1
glib2 2.86.2-1 -> 2.86.3-1
guile 3.0.10-1 -> 3.0.11-1
hwdata 0.401-1 -> 0.402-1
iproute2 6.17.0-1 -> 6.18.0-1
libarchive 3.8.3-1 -> 3.8.4-1
libcups 2:2.4.15-2 -> 2:2.4.16-1
libdeflate 1.24-1 -> 1.25-1
libidn2 2.3.7-1 -> 2.3.8-1
libnftnl 1.3.0-1 -> 1.3.1-1
libnl 3.11.0-1 -> 3.12.0-1
libpng 1.6.51-1 -> 1.6.53-1
libxkbcommon 1.13.0-1 -> 1.13.1-1
mesa 1:25.2.7-1 -> 1:25.3.1-2
nftables 1:1.1.5-1 -> 1:1.1.6-1
python 3.13.7-1 -> 3.13.11-1
zlib-ng 2.3.1-1 -> 2.3.2-1
``