[LWIP] update SConscript: add /src/include/posix to include path when RT_USING_DFS_NET not enable.

components/net/lwip-2.0.2/SConscript

@@ -67,6 +67,10 @@ path = [GetCurrentDir() + '/src',
     GetCurrentDir() + '/src/arch/include',
     GetCurrentDir() + '/src/include/netif']
 
+if not GetDepend('RT_USING_POSIX') or not GetDepend('RT_USING_DFS_NET'):
+    path += [GetCurrentDir() + '/src/include/posix']
+    print('include /src/include/posix')
+
 if GetDepend(['RT_LWIP_SNMP']):
     src += snmp_src
     path += [GetCurrentDir() + '/src/apps/snmp']