pull up r18840 from trunk

pull up r18840 from trunk

 r18840@cathode-dark-space:  jaltman | 2006-11-17 18:14:27 -0500
 ticket: new
 tags: pullup
 subject: reset use_master flag when master_kdc cannot be found

    krb5_get_init_creds_password:

 	if the master_kdc cannot be identified reset the use_master
    	flag.  otherwise, the krb5_get_init_creds("kadmin/changepw")
 	call will attempt to communicate with the master_kdc that
 	cannot be reached.

ticket: 4802

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/krb5-1-6@18849 dc483132-0cff-0310-8789-dd5450dbe970