coreutils: fixing cross-build

coreutils can't generate the man pages cross-building. I do a trick
to get them from a non-cross-built coreutils.

pkgs/tools/misc/coreutils/default.nix

@@ -6,7 +6,8 @@
 assert aclSupport -> acl != null;
 assert selinuxSupport -> libselinux != null && libsepol != null;
 
-stdenv.mkDerivation rec {
+let
+  self = stdenv.mkDerivation rec {
     name = "coreutils-8.21";
 
     src = fetchurl {
@@ -28,6 +29,20 @@ stdenv.mkDerivation rec {
         ++ stdenv.lib.optional (stdenv.gccCross.libc ? libiconv)
           stdenv.gccCross.libc.libiconv.crossDrv;
 
+      buildPhase = ''
+        make || (
+          pushd man
+          for a in *.x; do
+            touch `basename $a .x`.1
+          done
+          popd; make ) 
+      '';
+
+      postInstall = ''
+        rm $out/share/man/man1/*
+        cp ${self}/share/man/man1/* $out/share/man/man1
+      '';
+
       # Needed for fstatfs()
       # I don't know why it is not properly detected cross building with glibc.
       configureFlags = [ "fu_cv_sys_stat_statfs2_bsize=yes" ];
@@ -59,4 +74,6 @@ stdenv.mkDerivation rec {
 
       maintainers = [ stdenv.lib.maintainers.ludo ];
     };
-}
+  };
+in
+  self