Detect when drivers were added or removed

[holzingk]

At the moment you have to manually delete _grisp when there is a new or a deleted driver, otherwise you get an abscure build failure.

Perhaps we shoud automate that task, or at least give a better warning.

[peerst]

Agree

[eproxus]

It could be that we're "too smart" when it comes to the makefile patching. Maybe always reverting and patching the makefiles would solve the problem?

[sylane]

This would solve the problem, and it may be the simplest solution...