* pam_krb5afs.c: recognize bare boolean options as enabling them.
    * pam_krb5afs.c: recognize numeric options on the command line correctly.
    * pam_krb5afs.c: obtain v5 and v4 stash credentials with the new password
    	after successful password change operations.
    * pam_krb5afs.c: don't warn about expired passwords if we were passed the
    	"no_warn" option on the command line OR the PAM_SILENT flag was passed
    	to the function (previously, only PAM_SILENT was honored).