Note: this really belongs in liza-proguic, and should be moved in the near
future.
liza-proguic is being modified to generate step-level packages, which are
significantly faster to build than larger ones (XSLT TAME scales
terribly). These changes handle those new dependencies.
One important thing to note with this change is that suppliers.mk now
requires proguic to have run before generation so that those generated
dependencies can be properly examined. This is a quick operation, so that
is not problematic.
This also depends on the .version.xml change that was previously made: when
the timestamp changed every time, we got into an infinite build loop.