vsftpd: fix the CVE-2015-1419

Taken Patch from fedora to fix CVE-2015-1419, deny_file parsing to do
more what is expected.

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>