Merged lwip 2.0.2 stable path 1 from https://github.com/ARMmbed/lwip
Patch allows lwip to do autonomous address configuration for prefixes
that are not on-link.
ad7cf16 Add David's IPv6 improvements to CHANGELOG
af9d783 Fix (bogus) MSVC 2010 warning about uninitialized variable usage in ip6.c It's wrong because the variables are initialized during first loop iteration due to best_addr == NULL
68358d7 nd6: cull destination cache on router removal
7323fa1 nd6: some work on basic RFC 4861 compliance
10eb2ca ip6: improve source address selection
6c06ecd ip6/nd6: route using on-link prefixes, not addresses
9f1714d nd6: improve router selection
2486b41 netif: more ip6 state changes invoke status callback
519d809 nd6: fix Duplicate Address Detection
9f3c6dd nd6: check link status before sending packets
8c761a2 nd6: improve address autoconfiguration support
cd60f73 Merge branch 'mbed-os-lwip-rc2-maint' into mbed-os-lwip-rc2-maint-prefixed
3a50479 fixed bug #49676 (Possible endless loop when parsing dhcp options) & added unit test for that
git-subtree-dir: features/FEATURE_LWIP/lwip-interface/lwip
git-subtree-split: cd60f73f110829e00df46593fea5db26bcfb1662