Enable BangPatterns for ghc and hadrian projects by default.

compiler/ghc.cabal.in

@@ -96,8 +96,10 @@ Library
     if flag(dynamic-system-linker)
         CPP-Options: -DCAN_LOAD_DLL
 
-    Other-Extensions:
+    Default-Extensions:
         BangPatterns
+
+    Other-Extensions:
         CPP
         DataKinds
         DeriveDataTypeable

ghc/ghc-bin.cabal.in

@@ -73,8 +73,9 @@ Executable ghc
             GHCi.UI.Monad
             GHCi.UI.Tags
             GHCi.Util
-        Other-Extensions:
+        Default-Extensions:
             BangPatterns
+        Other-Extensions:
             FlexibleInstances
             LambdaCase
             MagicHash

hadrian/hadrian.cabal

@@ -130,6 +130,7 @@ executable hadrian
                        , RecordWildCards
                        , ScopedTypeVariables
                        , TupleSections
+                       , BangPatterns
     other-extensions:    MultiParamTypeClasses
                        , TypeFamilies
     build-depends:       base                 >= 4.8     && < 5