Bug#891048: gtk-d: Fix ldflags issue (from Ubuntu)

[Jeremy Bicha]

Source: gtk-d
Version: 3.7.1-1

Ubuntu has been carrying a gtk-d diff to fix an LDFLAGS issue.
Matthias Klumpp said he might have a way to handle this better, so I'm
filing this bug to help as a reminder.

http://ubuntudiff.debian.net/?query=-FPackage+gtk-d

Thanks,
Jeremy Bicha