[gnome-shell] build: Don't use libdir for systemd unit path

[Jonas Ådahl <jadahl src gnome org>]

commit 43e8dfacb45e470d02d3880ceb28a4494262f4c9
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Jul 18 23:03:30 2018 +0200

    build: Don't use libdir for systemd unit path
    
    Some systems define it to /usr/lib64 on 64-bit systems, which is not
    where systemd looks for unit files. Just hardcode 'lib' in the install
    prefix until we get to use the pkg-config file.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/424

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 7e5fe3832..65f6c7f1f 100644
--- a/meson.build
+++ b/meson.build
@@ -64,7 +64,7 @@ plugindir = get_variable('BROWSER_PLUGIN_DIR', mozplugindir)
 # systemduserunitdir = systemd_dep.get_pkgconfig_variable('systemduserunitdir',
 #                                                         define_variable: ['prefix', prefix])
 # and uncomment systemd_dep below
-systemduserunitdir = join_paths(libdir, 'systemd', 'user')
+systemduserunitdir = join_paths(prefix, 'lib', 'systemd', 'user')
 
 keybindings_dep = dependency('gnome-keybindings', required: false)
 if keybindings_dep.found()