Three fixes for compatibility with GHC 7.8

Two of the fixes were in the custom version of the binary package. We
should get rid of it at some point, to reduce the maintenance burden.

The third fix was to add new version constraints for happy and alex in
gf.cabal. New versions of them are needed because of the ugly, low-level,
GHC-specific code they produce need to be different for GHC 7.8.

More fixes might be needed for -server mode, but the cgi package is not
compatible with GHC 7.8 at the moment, so it will have to wait.

gf.cabal

@@ -159,7 +159,12 @@ Executable gf
 --if flag(new-comp)
 --  cpp-options: -DNEW_COMP
 
-  build-tools: happy, alex>=3
+  build-tools: happy
+
+  if impl(ghc>=7.8)
+    build-tools: happy>=1.19, alex>=3.1
+  else
+    build-tools: happy, alex>=3
 
   if os(windows)
     build-depends: Win32

src/binary/Data/Binary/Builder.hs

@@ -55,6 +55,7 @@ module Data.Binary.Builder (
   ) where
 
 import Foreign
+import System.IO.Unsafe(unsafePerformIO)
 import Data.Monoid
 --import Data.Word
 import qualified Data.ByteString      as S

src/binary/Data/Binary/Get.hs

@@ -89,6 +89,9 @@ import Control.Applicative (Applicative(..))
 import Foreign
 
 -- used by splitAtST
+#if MIN_VERSION_base(4,6,0)
+import Control.Monad.ST.Unsafe(unsafeInterleaveST)
+#endif
 import Control.Monad.ST
 import Data.STRef