[Net] Add `RT_USING_NETUTILS` to LwIP 2.0.2 SConscript.

components/net/lwip-2.0.2/SConscript

@@ -75,6 +75,10 @@ if GetDepend(['RT_LWIP_SNMP']):
 if GetDepend(['RT_LWIP_PPP']):
     src += ppp_src
     path += [GetCurrentDir() + '/src/netif/ppp']
+    
+# For testing apps
+if GetDepend(['RT_USING_NETUTILS']):
+    src += Glob('./apps/*.c')
 
 group = DefineGroup('lwIP', src, depend = ['RT_USING_LWIP', 'RT_USING_LWIP202'], CPPPATH = path)