Fix missing escape in macro
Fix missing escape in macro

Reviewers: angerman, austin, bgamari, erikd, simonmar

Reviewed By: angerman

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3727

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