This creates kernel-core and kernel-drivers subpackages. The kernel package
remains as a meta-package the requires both of the subpackages. This allows
most installs to continue on as-is with upgrades working.
The contents of the kernel-core and kernel-drivers subpackages are determined
at build time through the filter-modules.sh script. This script "removes"
pre-defined subsystems and modules and generates a filelist for the %files
section of each subpackage. The contents of each are per-arch, with arch
override files taken into account. This allows us to make the split useful
for varying arches.