sbcl: fix build on Darwin

Coreutils v9.8 has a regression on Darwin that causes
`__CF_USER_TEXT_ENCODING` env var to get added to `env`’s output. This
causes a test failure. So get the variant of `env` from
darwin.shell_cmds instead (and `uname`, to avoid having both pkgs in the
closure).

I submitted a bug report to Coreutils, but it is not yet in the tracker
or list archives for me to link from here.

pkgs/development/compilers/sbcl/default.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   callPackage,
+  darwin,
   ecl,
   coreutils,
   fetchurl,
@@ -69,6 +70,7 @@ let
       "${sbclBootstrap}/bin/sbcl --disable-debugger --no-userinit --no-sysinit"
     else
       "${lib.getExe ecl} --norc";
+  posixUtils = if stdenv.hostPlatform.isDarwin then darwin.shell_cmds else coreutils;
 
 in
 
@@ -188,8 +190,8 @@ stdenv.mkDerivation (self: {
         # definitely NOT be patched this way, hence just a single * (and no
         # globstar).
         substituteInPlace ${if self.purgeNixReferences then "tests" else "{tests,src/code}"}/*.{lisp,sh} \
-          --replace-quiet /usr/bin/env "${coreutils}/bin/env" \
-          --replace-quiet /bin/uname "${coreutils}/bin/uname" \
+          --replace-quiet /usr/bin/env "${posixUtils}/bin/env" \
+          --replace-quiet /bin/uname "${posixUtils}/bin/uname" \
           --replace-quiet /bin/sh "${stdenv.shell}"
       )
       # Official source release tarballs will have a version.lispexpr, but if you