[gnome-settings-daemon] build: Don't enable backlight helper if GUdev is not available

[Bastien Nocera <hadess src gnome org>]

commit b0257aecd580ee5230ba9e6bdc50c25e3ecc6b4f
Author: Michael Biebl <biebl debian org>
Date:   Thu Jun 14 23:00:41 2012 +0200

    build: Don't enable backlight helper if GUdev is not available
    
    We should check for have_gudev, not enable_gudev in this case.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=676407

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index cf6b452..4430aeb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -208,7 +208,7 @@ fi
 # ---------------------------------------------------------------------------
 PKG_CHECK_MODULES(POWER, upower-glib >= $UPOWER_REQUIRED_VERSION gnome-desktop-3.0 >= $GNOME_DESKTOP_REQUIRED_VERSION libcanberra-gtk3 libnotify x11 xext)
 
-if test x$enable_gudev != xno; then
+if test x$have_gudev != xno; then
 	PKG_CHECK_MODULES(BACKLIGHT_HELPER,
 		glib-2.0 >= $GLIB_REQUIRED_VERSION
 		gudev-1.0