Remember the AvailInfo for each IE

Authored by alexbiehl on Sep 4 2017, 6:59 AM.

Description

Remember the AvailInfo for each IE

This is another take on https://phabricator.haskell.org/D3844.

This patch removes then need for haddock to reimplement the calculation
of exported names from modules. Instead when renaming export lists ghc
annotates each IE with its exported names.

Haddocks current export logic has caused lots of trouble in the past
(on the Github issue tracker):

Updates haddock submodule.

Reviewers: austin, bgamari, ezyang

Reviewed By: bgamari, ezyang

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3864