[gnome-desktop/wjt/fix-unused-function-without-systemd] systemd: Avoid unused function warning when disabled

[Will Thompson <wjt src gnome org>]

commit f18dee1d20f2fb831a9baea462132cb67ee63206
Author: Will Thompson <will willthompson co uk>
Date:   Thu Dec 16 21:18:48 2021 +0000

    systemd: Avoid unused function warning when disabled
    
    If the project is configured to build without systemd support, this
    function is unused.
    
    If one is foolish enough to also build with -Werror, as I am, then this
    the resulting unused-function warning is fatal and one is sad.

 libgnome-desktop/gnome-systemd.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/libgnome-desktop/gnome-systemd.c b/libgnome-desktop/gnome-systemd.c
index 89e0a423..3773f3ba 100644
--- a/libgnome-desktop/gnome-systemd.c
+++ b/libgnome-desktop/gnome-systemd.c
@@ -143,6 +143,7 @@ on_bus_gotten_cb (GObject      *source,
 }
 #endif
 
+#ifdef HAVE_SYSTEMD
 static gchar *
 systemd_unit_name_escape (const gchar *in)
 {
@@ -158,6 +159,7 @@ systemd_unit_name_escape (const gchar *in)
     }
   return g_string_free (str, FALSE);
 }
+#endif
 
 /**
  * gnome_start_systemd_scope: