quartz-wm: --enable-xplugin-dock-support

This is required to avoid using a proprietary binary, which doesn't
even exist for aarch64.

pkgs/servers/x11/quartz-wm/default.nix

···
     ./no_title_crash.patch
     ./extern-patch.patch
   ];
+  configureFlags = [ "--enable-xplugin-dock-support" ];
   nativeBuildInputs = [ pkg-config ];
   buildInputs = [
     xorg.libXinerama