d/rules: Increase arbitrary test timeouts

Latest round of builds timed out on armel and armhf. To fix it, do what's been done already with eg. gnome-shell [1] or glib2.0 [2]. No reason to diverge, so I re-use the same values and include the same comment 'as is' (credits to smcv).

[1] fd5a465efd6b3819200b708b7c641e2f8f2d6011 [2] cabc4572ee2544e93625dc3e0d7564a5300cae23