ghc-8.0.2: add sphinx to inputs for documentation

Closes https://github.com/NixOS/nixpkgs/pull/21434.

pkgs/development/compilers/ghc/8.0.2.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl, fetchpatch, bootPkgs, perl, gmp, ncurses, libiconv, binutils, coreutils
-, hscolour, patchutils
+, hscolour, patchutils, sphinx
 }:
 
 let
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
 
   patches = [] ++ stdenv.lib.optional stdenv.isLinux ./ghc-no-madv-free.patch;
 
-  buildInputs = [ ghc perl hscolour ];
+  buildInputs = [ ghc perl hscolour sphinx ];
 
   enableParallelBuilding = true;
 

pkgs/top-level/haskell-packages.nix

@@ -50,6 +50,7 @@ rec {
     ghc802 = callPackage ../development/compilers/ghc/8.0.2.nix rec {
       bootPkgs = packages.ghc7103;
       inherit (bootPkgs) hscolour;
+      sphinx = pkgs.python27Packages.sphinx;
     };
     ghcHEAD = callPackage ../development/compilers/ghc/head.nix rec {
       bootPkgs = packages.ghc7103;