autorandr: install zsh completions

autorandr includes functional zsh completions upstream they just lack
a make target to install the relevant file. For some consistency use the
direct file for both zsh and bash rather than just zsh. Note this
changes the resulting bash completion filename from just 'autorandr' to
'autorandr.bash'

See https://github.com/phillipberndt/autorandr/issues/197

pkgs/tools/misc/autorandr/default.nix

@@ -2,7 +2,8 @@
 , python3Packages
 , fetchFromGitHub
 , systemd
-, xrandr }:
+, xrandr
+, installShellFiles }:
 
 stdenv.mkDerivation rec {
   pname = "autorandr";
@@ -10,6 +11,8 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ python3Packages.python ];
 
+  nativeBuildInputs = [ installShellFiles ];
+
   # no wrapper, as autorandr --batch does os.environ.clear()
   buildPhase = ''
     substituteInPlace autorandr.py \
@@ -23,7 +26,12 @@ stdenv.mkDerivation rec {
     runHook preInstall
     make install TARGETS='autorandr' PREFIX=$out
 
-    make install TARGETS='bash_completion' DESTDIR=$out/share/bash-completion/completions
+    # zsh completions exist but currently have no make target, use
+    # installShellCompletions for both
+    # see https://github.com/phillipberndt/autorandr/issues/197
+    installShellCompletion --cmd autorandr \
+        --bash contrib/bash_completion/autorandr \
+        --zsh contrib/zsh_completion/_autorandr
 
     make install TARGETS='autostart_config' PREFIX=$out DESTDIR=$out