add RT_USING_MINILIBC in building script.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@670 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/libc/minilibc/SConscript

@@ -4,7 +4,7 @@ Import('RTT_ROOT')
 # The set of source files associated with this SConscript file.
 src_local = Glob('*.c')
 
-env.Append(CPPPATH = RTT_ROOT + '/components/libc/minilibc')
+env.Append(CPPPATH = RTT_ROOT + '/components/libc/minilibc', CPPDEFINES='RT_USING_MINILIBC')
 
 obj = env.Object(src_local)
 Return('obj')