update_engine: add back missing header file

[kcxt]

update_engine had a header file removed that for some reason can't be found on hybris based builds on the OnePlus 6 at least, add back the header to make it happy.

[kcxt]

This is also needed for the Pixel 2 XL. Can we get it merged? :D

[NotKit]

Which repo is it supposed to come from originally?

[kcxt]

@NotKit It's from https://github.com/LineageOS/android_system_update_engine, it got removed (and I think moved to a different repo that isn't included in halium 9 builds).

[NotKit]

@calebccff do you know which repo it got moved to? If possible, I'd prefer to get that repo back to minimize amount of changes we add on top. On the other hand, update_engine itself does not make sense in Halium builds and can be safely removed from device trees.

[kcxt]

@calebccff do you know which repo it got moved to? If possible, I'd prefer to get that repo back to minimize amount of changes we add on top. On the other hand, update_engine itself does not make sense in Halium builds and can be safely removed from device trees.

I don't know where it went... Removing update_engine does seem like a more sensible solution. @NotKit

[kcxt]

I had a look at removing update_engine but it doesn't seem massively feasible, then again I'm not particularly comfortable working with Android build files. Unless there's a good reason not to it's probably easiest to keep this patch.

[Herrie82]

I thought we normally remove update engine from builds? It's not something we should need anyway?

[Thaodan]

Update engine can be disabled I think. We disable update_verifier for hybris already.