Simon Marlow authored Sep 28, 2017 and Ben Gamari committed Sep 28, 2017

The strictness signature for a data con wrapper wasn't including any
dictionary arguments, which meant that bangs on the fields of a
constructor with an existential context would be moved to the wrong
fields.  See T14290 for an example.

Test Plan:
* New test T14290
* validate

Reviewers: simonpj, niteria, austin, bgamari, erikd

Reviewed By: simonpj, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #14290

Differential Revision: https://phabricator.haskell.org/D4040