_389-ds-base: disable parallel installing

Without the change parallel installs fail occasionally as:

    ld: cannot find -lslapd: No such file or directory

Full build log example: https://hydra.nixos.org/log/h38bj77gav0r6jbi4bgzy1lfjq22k2wy-389-ds-base-2.3.1.drv

pkgs/servers/ldap/389/default.nix

@@ -119,6 +119,10 @@ stdenv.mkDerivation rec {
   ];
 
   enableParallelBuilding = true;
+  # Disable parallel builds as those lack some dependencies:
+  #   ld: cannot find -lslapd: No such file or directory
+  # https://hydra.nixos.org/log/h38bj77gav0r6jbi4bgzy1lfjq22k2wy-389-ds-base-2.3.1.drv
+  enableParallelInstalling = false;
 
   doCheck = true;