[commit: ghc] ghc-8.4: Bump Cabal submodule (c6cf13c)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : ghc-8.4
Link       : http://ghc.haskell.org/trac/ghc/changeset/c6cf13ca63f3a11a8da7c7e3bd69e673a8df5440/ghc

>---------------------------------------------------------------

commit c6cf13ca63f3a11a8da7c7e3bd69e673a8df5440
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Thu Dec 21 15:04:05 2017 -0500

    Bump Cabal submodule
    
    (cherry picked from commit e237e1f132d0c0e1d9bf24d21cf688110305fb28)


>---------------------------------------------------------------

c6cf13ca63f3a11a8da7c7e3bd69e673a8df5440
 libraries/Cabal         | 2 +-
 utils/ghc-cabal/Main.hs | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/libraries/Cabal b/libraries/Cabal
index 97c66f2..3f20e1f 160000
--- a/libraries/Cabal
+++ b/libraries/Cabal
@@ -1 +1 @@
-Subproject commit 97c66f2c7698f0aea4277acb66b918b7341b3d01
+Subproject commit 3f20e1faf9bc86ecb154ccf3e8b913bff14b9264
diff --git a/utils/ghc-cabal/Main.hs b/utils/ghc-cabal/Main.hs
index 440ab0b..f330ce0 100644
--- a/utils/ghc-cabal/Main.hs
+++ b/utils/ghc-cabal/Main.hs
@@ -95,11 +95,11 @@ runDefaultMain
       gpdFile <- defaultPackageDesc verbosity
       gpd <- readPackageDescription verbosity gpdFile
       case buildType (flattenPackageDescription gpd) of
-          Just Configure -> defaultMainWithHooks autoconfUserHooks
+          Configure -> defaultMainWithHooks autoconfUserHooks
           -- time has a "Custom" Setup.hs, but it's actually Configure
           -- plus a "./Setup test" hook. However, Cabal is also
           -- "Custom", but doesn't have a configure script.
-          Just Custom ->
+          Custom ->
               do configureExists <- doesFileExist "configure"
                  if configureExists
                      then defaultMainWithHooks autoconfUserHooks
@@ -266,7 +266,7 @@ generate directory distdir config_args
       writePersistBuildConfig distdir lbi
 
       hooked_bi <-
-           if (buildType pd0 == Just Configure) || (buildType pd0 == Just Custom)
+           if (buildType pd0 == Configure) || (buildType pd0 == Custom)
            then do
               maybe_infoFile <- defaultHookedPackageDesc
               case maybe_infoFile of