nsd: ensure patches can be overridden

Because the package replaced patchPhase entirely, using overrideAttrs to
add additional patches did not work. If we need to carry patches here in
the future, this will also get in the way. Fix this by moving the
current patch code to postPatch.

This removes the dead code with a todo on it; the package worked before
with that code being dead, so let's not change it right now.

pkgs/by-name/ns/nsd/package.nix

@@ -57,12 +57,8 @@ stdenv.mkDerivation (finalAttrs: {
 
   enableParallelBuilding = true;
 
-  # TODO: prePatch doesn't actually get executed because patchPhase is overridden
-  prePatch = ''
-    substituteInPlace nsd-control-setup.sh.in --replace openssl ${openssl}/bin/openssl
-  '';
-
-  patchPhase = ''
+  # Prevent the install script from copying nsd.conf.sample into /etc/nsd.
+  postPatch = ''
     sed 's@$(INSTALL_DATA) nsd.conf.sample $(DESTDIR)$(nsdconfigfile).sample@@g' -i Makefile.in
   '';