[devhelp] window: add missing header

[Aleksander Morgado <aleksm src gnome org>]

commit 8cb5256594641e11fd9633e58d378d52d9492808
Author: Aleksander Morgado <aleksander lanedo com>
Date:   Sat Mar 3 15:47:38 2012 +0100

    window: add missing header
    
    sqrt() needs to explicitly add <math.h>

 src/dh-window.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/dh-window.c b/src/dh-window.c
index 9944a7f..f26895e 100644
--- a/src/dh-window.c
+++ b/src/dh-window.c
@@ -27,6 +27,7 @@
 
 #include "config.h"
 #include <string.h>
+#include <math.h>
 #include <glib/gi18n-lib.h>
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>