Use C99's bool

Authored by bgamari on Nov 29 2016, 3:51 PM.

Description

Use C99's bool

Test Plan: Validate on lots of platforms

Reviewers: erikd, simonmar, austin

Reviewed By: erikd, simonmar

Subscribers: michalt, thomie

Differential Revision: https://phabricator.haskell.org/D2699