add module Mains for picky versions of ghc

config-joey.hs

@@ -1,4 +1,5 @@
 -- This is the live config file used by propellor's author.
+module Main where
 
 import Propellor
 import Propellor.CmdLine

propellor.hs

@@ -12,6 +12,8 @@
 -- The source is either copied from /usr/src/propellor, or is cloned from
 -- git over the network.
 
+module Main where
+
 import Utility.UserInfo
 import Utility.Monad
 import Utility.Process