Update waf to 2.1.4 : rtems/pkg/rtems-lwip

Summary

The latest verison of waf fixes several issues on Windows. We also have a huge inconsistency in the version we're running which we should probably fix:

./rtems-deployment/waf       waf 2.0.24 (1af97c71f5a6756abf36d0f78ed8fd551596d7cb)
./rtems-docs/waf             waf 2.1.3 (ee9a11d51e94d31c548fd5b6a8103c68327b3354)
./rtems-examples/waf         waf 2.0.25 (2db0b41b2805cd5db3b55476c06b23c1e46d319f)
./rtems-libbsd/waf           waf 2.0.25 (2db0b41b2805cd5db3b55476c06b23c1e46d319f)
./rtems-littlevgl/waf        waf 2.0.25 (2db0b41b2805cd5db3b55476c06b23c1e46d319f)
./rtems-lwip/waf             waf 2.0.18 (314689b8994259a84f0de0aaef74d7ce91f541ad)
./rtems-net-legacy/waf       waf 2.1.2 (8504c212ce81919a5858a5118570613422338852)
./rtems-net-services/waf     waf 2.0.25 (2db0b41b2805cd5db3b55476c06b23c1e46d319f)
./rtems-tools/waf            waf 2.1.2 (8504c212ce81919a5858a5118570613422338852)
./rtems/waf                  waf 2.1.3 (ee9a11d51e94d31c548fd5b6a8103c68327b3354)

Steps to reproduce

Pre-set options