pull up r19477 from trunk

pull up r19477 from trunk

 r19477@cathode-dark-space:  jaltman | 2007-04-17 14:06:15 -0400
 ticket: 5532
 tags: pullup

 In testing it has been observed that remote desktop connections
 will execute the NPLogonNotify function but if the logon is
 re-connecting to an existing session, the LogonScript is ignored.
 This leaves orphaned credential cache files.

 This commit adds a function, KFW_cleanup_orphaned_caches, which
 is called by NPLogonNotify to delete any orphaned cache files.
 An orphaned cache file is one that is older than five minutes.

ticket: 5532
version_fixed: 1.6.1

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-6@19486 dc483132-0cff-0310-8789-dd5450dbe970