Fabrice Bellet authored Apr 19, 2016 and Olivier Crête committed Jun 21, 2017

This patch completes the previous patch by adding a link back from the
discovered pair, to the parent pair that generated this check. This link
is needed by the ICE spec, to comply with section 8.1.1.1, "Regular
nomination", where the check to be retriggered is the initial check that
caused the discovery of the valid pair. When the valid pair is a
peer-reflexive pair, the retriggered check must target the succeeded
pair, and not the valid discovered pair.

Differential Revision: https://phabricator.freedesktop.org/D879