Include <stdlib.h> to get prototype for abs() function.

diff --git a/programs/wineconsole/dialog.c b/programs/wineconsole/dialog.c
index 4861254..a930d34 100644
--- a/programs/wineconsole/dialog.c
+++ b/programs/wineconsole/dialog.c
@@ -4,6 +4,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include "commctrl.h"
 #include "prsht.h"
 #include "winecon_user.h"