runqueue: Improve handling of failing setscene tasks with hard dependencies

If a setscene task has a hard dependency on a task like pseudo-native, its
expected that the setscene task will not run unless the dependency is met.

This adds code to ensure that is the case, otherwise a bug would show up
with a usecase like:

bitbake gnome-common
bitbake pseudo-native -c cleansstate
bitbake gnome-common -c clean
bitbake gnome-common

With the double wrapper script environment, we'd not see issues like
this as it would be masked. The problem theoretically affects code like
useradd too as well as anything using a sstate postinstall.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>