stdenv-setup and misc pkgs: Revert to space-deliminated propagated-* files

We cannot switch to line-delimited yet, because certain Nix commands do
not read in the entire file, but just the first line.

pkgs/stdenv/generic/builder.sh

@@ -15,5 +15,5 @@ cat "$setup" >> $out/setup
 # in stdenv.
 mkdir $out/nix-support
 if [ "$propagatedUserEnvPkgs" ]; then
-    printf '%s\n' $propagatedUserEnvPkgs > $out/nix-support/propagated-user-env-packages
+    printf '%s ' $propagatedUserEnvPkgs > $out/nix-support/propagated-user-env-packages
 fi