* src/pwck.c: Document the sections closed by #endif

* src/pwck.c, man/pwck.8.xml: No alternative shadow file can be
	given when USE_TCB is enabled.

TODO

@@ -115,6 +115,7 @@ ALL:
     entry (with a password).
   - Add check to move passwd passwords to shadow if there is a shadow
     file.
+  - Support an alternative /etc/tcb directory as second parameter.
 
 - su
   - add a login.defs configuration parameter to add variables to keep in