pkgtools/gnome-packagekit: Stop detecting deprecation

I originally was trying to patch set-but-not-used errors but then
quickly found out that a new glib also introduced numerous breakages
due to -Werror breaking on g_thread_init deprecation.  Between the
two problems I had already generated 10 patches with no end in site.

Rather than continue, address the real issue and remove -Werror from
this old package.

(marino)