autoPatchelfHook: Run after patchelf's setup hook

So far the runtimeDependencies variable has been rather useless unless
you also set dontPatchelf, because the patchelf setup hook ran *after*
the autoPatchelfHook and thus stripped off the additional RPATHs added
using runtimeDependencies.

I did this by moving the autoPatchelfHook to be run in postFixup instead
of fixupOutput, however I needed to replicate the for loop that runs the
hook on all outputs.

Until we have a way to influence order of execution for hooks I've
marked this with an XXX so that we can use fixupOutput again.

Tested this against all packages that use autoPatchelfHook using the
following and checking whether the output contains any errors concerning
shared libraries:

nix-build -E 'with import ./. { config.allowUnfree = true; };
  runCommand "test-executables" {
    drvs = [
      masterpdfeditor franz zoom-us anydesk teamviewer maxx
      oracle-instantclient cups-kyodialog3 virtlyst powershell
    ];
  } "for i in $drvs; do for b in $i/bin/*; do \"$b\" || :; done; done"
'

Signed-off-by: aszlig <aszlig@nix.build>
Fixes: https://github.com/NixOS/nixpkgs/issues/43082
Cc: @Ericson2314