Merge #153104: linux-pam: don't create dangling symlink during build

... into staging

nixos/modules/security/pam.nix

···
         setuid = true;
         owner = "root";
         group = "root";
-        source = "${pkgs.pam}/sbin/unix_chkpwd.orig";
+        source = "${pkgs.pam}/bin/unix_chkpwd";
       };
     };
 

pkgs/os-specific/linux/pam/default.nix

···
 
   enableParallelBuilding = true;
 
-  postInstall = ''
-    mv -v $out/sbin/unix_chkpwd{,.orig}
-    ln -sv /run/wrappers/bin/unix_chkpwd $out/sbin/unix_chkpwd
-  ''; /*
-    rm -rf $out/etc
-    mkdir -p $modules/lib
-    mv $out/lib/security $modules/lib/
-  '';*/
-  # don't move modules, because libpam needs to (be able to) find them,
-  # which is done by dlopening $out/lib/security/pam_foo.so
-  # $out/etc was also missed: pam_env(login:session): Unable to open config file
-
   preConfigure = lib.optionalString (stdenv.hostPlatform.libc == "musl") ''
       # export ac_cv_search_crypt=no
       # (taken from Alpine linux, apparently insecure but also doesn't build O:))