Log Message:
incorporate patch from othersrc/libexec/tnftpd to honour --sysconfdir
(will be included in the next release) and make the package honour
PKG_SYSCONFDIR.

use CONF_FILES to install the sample configuration ftpd.conf and
ftpusers.

bump PKGREVISION, as the default configuration file location has
changed to ${PKG_SYSCONFDIR}. set PKG_SYSCONFDIR.tnftpd=/etc to get
the previous behaviour.