have only been defined if MOZILLA_OFFICIAL was set, but it didn't work
right at all.
i've commented out the offending lines for now, until it is determined how we go
about rolling version numbers in the new world.
status. This is needed for fullcircle, but it's also the right thing to do.
so add a target for build_number, and add it as a dependency to the export target
This affects win only, and I've tested it.
