Adam Gundry authored Oct 02, 2020 and Marge Bot committed Dec 24, 2020

This patch significantly refactors key renamer datastructures (primarily Avail
and GlobalRdrElt) in order to treat DuplicateRecordFields in a more robust way.
In particular it allows the extension to be used with pattern synonyms (fixes
where mangled record selector names could be printed instead of field labels
(e.g. with -Wpartial-fields or hole fits, see new tests).

The key idea is the introduction of a new type GreName for names that may
represent either normal entities or field labels.  This is then used in
GlobalRdrElt and AvailInfo, in place of the old way of representing fields
using FldParent (yuck) and an extra list in AvailTC.

Updates the haddock submodule.