add demo_view_dc_buffer.c to SConscript

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@581 bbd45198-f89e-11dd-88c7-29a3b14d5316

examples/gui/SConscript

 Import('env')
 
 src_local = Split("""
+demo_view_dc_buffer.c
 demo_fnview.c
 demo_listview.c
 demo_panel_single.c