ocheron authored Sep 19, 2017 and Ben Gamari committed Sep 19, 2017

The function existed in integer-gmp-0.5.1.0 but was removed as
part of integer-gmp2 rewrite in #9281.  This is to bring it back.

Test Plan: Case integerGmpInternals, with GMP 4.3.2 and GMP 6.1.2

Reviewers: austin, hvr, goldfire, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3947