Narrow scope of special-case for unqualified printing of names in core libraries
Commit 547c597112954353cef7157cb0a389bc4f6303eb modifies the
pretty-printer to render names from a set of core packages (base,
ghc-prim, template-haskell) as unqualified. The idea here was that
many of these names typically are not in scope but are well-known by the
user and therefore qualification merely introduces noise.
This, however, is a very large hammer and potentially breaks any
consumer who relies on parsing GHC output (hence Trac #11208). This commit
partially reverts this change, now only printing Constraint (which
appears quite often in errors) as unqualified.
Fixes Trac #11208.
Updates tests in array submodule.
Test Plan: validate
Reviewers: hvr, thomie, austin
Differential Revision: https://phabricator.haskell.org/D1619
GHC Trac Issues: Trac #11208