shadow: Update login.defs to remove reference to cracklib

shadow: Update login.defs to remove reference to cracklib

- From shadow-15.0.0 all references to cracklib were removed from shadow. Apparently
   some functions were no longer accessible and the shadow team decided to remove cracklib
   references completely. This was not mentioned in the changelkog for 15.0.0
- This resulkts in gettinbg the message configuration error - unknown item
   'CRACKKLIB_DICTPATH' ( notify administrator ) when logging in to the console.
- The login to the console occurs successfully so the message is only a warning that
   cracklib is no longer used.
- IPfire does not use cracklkib anyway so this patch removes the section referring to
   cracklib from the login.defs configuration file.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>