[__postfix] Automagically support more OSs by not checking too much.

It is quite likely that the package is going to be called postfix, rather
than trying to have an exhaustive "allow list" for this package, we can
just add special cases for OSs where that is not the case (not aware of any
atm).

cdist/conf/type/__postfix/manifest

@@ -19,16 +19,4 @@
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
 
-
-os=$(cat "$__global/explorer/os")
-
-case "$os" in
-   alpine|ubuntu|debian|archlinux|suse|scientific|centos|devuan)
-      __package postfix --state present
-   ;;
-   *)
-      echo "Your operating system ($os) is currently not supported by this type (${__type##*/})." >&2
-      echo "Please contribute an implementation for it if you can." >&2
-      exit 1
-   ;;
-esac
+__package postfix --state present