nvidia-settings dependencies

[Mackenzie Morgan]

Hi there
In Ubuntu we received a few bug reports from users trying to use
nvidia-settings on KDE systems who found that it couldn't write to
their xorg.conf file.  It's been tracked to a lack of python-gtk2 on
KDE-based installs. While marking duplicates on those bugs in Ubuntu's
bugtracker, I came across one that also named pkg-config as a missing
dependency. I see from code inspection that it is required by
nvidia-settings but is also not in debian/control.  The packages in
Ubuntu are being updated to include these dependencies, but I figure
it's a good idea to let y'all know about the issue so those two
dependencies can be added in Debian as well.

Thanks
Mackenzie Morgan