cerbero-uninstalled: Allow Arch Linux to use ./cerbero-uninstalled
In Arch Linux the path /usr/bin/pacman
exists and this led the script to
think it's been running in a Windows without the appropriate MSYS
environment. Use the bash OSTYPE env var to make sure we're in a msys OS
before do the MSYS checks.
NOTE: I do not have access to a Windows machine with MSYS right now to test this properly. I only tested it in Arch Linux.
Edited by Carlos Falgueras García