Bug#814686: uscan, uupdate: vesion=4 and --destdir

[Osamu Aoki]

Package: devscripts
Version: 2.16.1
Severity: important

Though recent upload fixed regression bugs #809662 and #814559 for
version=3 watch files used with --destdir or USCAN_DESTDIR="../tarballs"
set.

But the new uupdated syntax is need to support these for version=4 watch
file invoked with --destdir or USCAN_DESTDIR="../tarballs".

Osamu