Merge pull request #34172 from deepfire/x-ghc-8.4-master

ghc841: update to 8.4.1-alpha2

pkgs/development/compilers/ghc/8.4.1.nix

···
   # platform). Static libs are always built.
   enableShared ? true
 
-, version ? "8.4.20180115"
+, version ? "8.4.20180122"
 }:
 
 assert !enableIntegerSimple -> gmp != null;
···
 
   src = fetchgit {
     url = "git://git.haskell.org/ghc.git";
-    rev = "3e3a096885c0fcd0703edbeffb4e47f5cbd8f4cc";
-    sha256 = "06slymbsd7vsfp4hh40v7cxf7nmp0kvlni2wfq7ag5wlqh04slgs";
+    rev = "61db0b8941cfb7ed8941ed29bdb04bd8ef3b71a5";
+    sha256 = "15sbpgkal4854jc1xn3sprvpnxwdj0fyy43y5am0h9vja3pjhjyi";
   };
 
   enableParallelBuilding = true;