fix compiling warning.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@968 bbd45198-f89e-11dd-88c7-29a3b14d5316

examples/gui/demo_view_window.c

@@ -15,7 +15,7 @@
 static struct rtgui_timer *timer;
 static struct rtgui_label* label;
 static struct rtgui_win* msgbox = RT_NULL;
-static rt_uint8_t label_text[80];
+static char label_text[80];
 static rt_uint8_t cnt = 5;
 
 /* 获取一个递增的窗口标题 */