sympow: don't use placeholder

pkgs/development/libraries/science/math/sympow/default.nix

@@ -34,11 +34,13 @@ stdenv.mkDerivation rec {
     makeWrapper "$out/share/sympow/sympow" "$out/bin/sympow" \
       --run 'export SYMPOW_LOCAL="$HOME/.local/share/sympow"' \
       --run 'if [ ! -d "$SYMPOW_LOCAL" ]; then
-        mkdir -p "$SYMPOW_LOCAL" 
-        cp -r ${placeholder "out"}/share/sympow/* "$SYMPOW_LOCAL"
+        mkdir -p "$SYMPOW_LOCAL"
+        cp -r @out@/share/sympow/* "$SYMPOW_LOCAL"
         chmod -R +xw "$SYMPOW_LOCAL"
     fi' \
       --run 'cd "$SYMPOW_LOCAL"'
+    substituteInPlace $out/bin/sympow --subst-var out
+
     runHook postInstall
   '';