Build priority

[Anca Emanuel]

The current algorithm for building 12000 packages for an new architecture is:
For a* to z* try build.
Of course you will need lib* and *dev first, and you will waste a lot
of time trying to compile things.
And a lot of (manual) retries.

My proposal: try to find an algorithm for dependencies.
If package A depends on package B to be build, B gets an +1 for priority.
Do that for the entire archive.