Fix Win32 x86 build validation after D2756
Fix Win32 x86 build validation after D2756

Test Plan: ./validate

Reviewers: austin, bgamari, erikd, simonmar

Reviewed By: simonmar

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2825

sdiehl/ghc,sdiehl/ghc,shlevy/ghc,sdiehl/ghc,ezyang/ghc,olsner/ghc,olsner/ghc,shlevy/ghc,ezyang/ghc,sdiehl/ghc,shlevy/ghc,sdiehl/ghc,sdiehl/ghc,shlevy/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc,olsner/ghc,olsner/ghc,olsner/ghc,shlevy/ghc,ezyang/ghc,olsner/ghc,ezyang/ghc,ezyang/ghc,sdiehl/ghc,ezyang/ghc,olsner/ghc