With the new way of treating dependencies, we need to properly
manage -pass1 packages: For that we need the installed version of
-pass1 packages. But it is recorded nowhere. packages.xml shouldn't
be used for that, because it is directly built from the book
dependencies: adding -pass1 packages would just duplicate the
dependency information. So the version has to be recorded in
the tracking file. This involves changing bump.xsl (this commit),
and passing the tracking file to gen_pkg_book (next commit).
