go_1_11: remove unused postConfigure

Since it was overriding configurePhase postConfigure has not be used in a while.

pkgs/development/compilers/go/1.11.nix

@@ -5,11 +5,6 @@ let
 
   inherit (stdenv.lib) optionals optionalString;
 
-  clangHack = writeScriptBin "clang" ''
-    #!${stdenv.shell}
-    exec ${stdenv.cc}/bin/clang "$@" 2> >(sed '/ld: warning:.*ignoring unexpected dylib file/ d' 1>&2)
-  '';
-
   goBootstrap = runCommand "go-bootstrap" {} ''
     mkdir $out
     cp -rf ${go_bootstrap}/* $out/
@@ -164,10 +159,6 @@ stdenv.mkDerivation rec {
     ulimit -a
   '';
 
-  postConfigure = optionalString stdenv.isDarwin ''
-    export PATH=${clangHack}/bin:$PATH
-  '';
-
   installPhase = ''
     cp -r . $GOROOT
     ( cd $GOROOT/src && ./all.bash )