zsh-completion: Move machine listing to autoload

Instead of having two different listings of machines, use an autoloaded
function that can be used by other shell completions in the future. It
will also allow editing a single file to change the way machinectl and
systemd-run completion for machines.

shell-completion/zsh/_machinectl

@@ -19,12 +19,7 @@
       case $cmd in
         list) msg="no options" ;;
         *)
-          _machines=( "${(foa)$(machinectl list | awk '{print $1}')}" )
-          if [[ -n "$_machines" ]]; then
-            _describe 'machines' _machines
-          else
-            _message 'no machines'
-          fi
+          _sd_machines
       esac
     else
       _message "no more options"

shell-completion/zsh/_sd_machines

@@ -0,0 +1,13 @@
+#autoload
+__get_machines () {
+        machinectl --full --no-pager list | {while read -r a b; do echo $a; done;};
+}
+
+local -a _machines
+_machines=("${(fo)$(__get_machines)}")
+typeset -U _machines
+if [[ -n "$_machines" ]]; then
+        _describe 'machines' _machines
+else
+        _message 'no machines'
+fi

shell-completion/zsh/_systemd-run

@@ -18,27 +18,12 @@ __slices () {
         _describe 'slices' _slices
 }
 
-__get_machines () {
-        machinectl --full --no-pager list | {while read -r a b; do echo $a; done;};
-}
-
-__machines () {
-        local -a _machines
-        _machines=("${(fo)$(__get_machines)}")
-        typeset -U _machines
-        if [[ -n "$_machines" ]]; then
-                _describe 'machines' _machines
-        else
-                _message 'no machines'
-        fi
-}
-
 _arguments \
         {-h,--help}'[Show help message]' \
         '--version[Show package version]' \
         '--user[Run as user unit]' \
         {-H+,--host=}'[Operate on remote host]:[user@]host:_sd_hosts_or_user_at_host' \
-        {-M+,--machine=}'[Operate on local container]:machines:__machines' \
+        {-M+,--machine=}'[Operate on local container]:machines:_sd_machines' \
         '--scope[Run this as scope rather than service]' \
         '--unit=[Run under the specified unit name]:unit name' \
         '--description=[Description for unit]:description' \