[gnome-settings-daemon] wacom: add missing config.h include

[Bastien Nocera <hadess src gnome org>]

commit 14937abcfbb56b65e2a0218818f8db5a4979e3e3
Author: Benjamin Tissoires <btissoir t440s banquise eu>
Date:   Thu Aug 28 15:02:43 2014 -0400

    wacom: add missing config.h include
    
    Without this, HAVE_GUDEV is not defined, and set_oled terminates
    abruptely, leaving out the possibility to set the OLEDs on the Intuos 4.
    
    As Bastien said "Not sure how we all missed that".
    
    https://bugzilla.gnome.org/show_bug.cgi?id=731977

 plugins/wacom/gsd-wacom-oled.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/plugins/wacom/gsd-wacom-oled.c b/plugins/wacom/gsd-wacom-oled.c
index 004edcf..b4b5a4f 100644
--- a/plugins/wacom/gsd-wacom-oled.c
+++ b/plugins/wacom/gsd-wacom-oled.c
@@ -17,6 +17,8 @@
  *
  */
 
+#include "config.h"
+
 #include <unistd.h>
 #include <math.h>
 #include <pango/pango.h>