It doesn't make sense in Qubes to rebuild modules at every VM startup.
Especially when modules dir is either read-only, or on non-persistent
root volume (TemplateBasedVM).
This is especially uneeded for dom0-provided kernels, which already have
u2mfn module built, but DKMS try to rebuild it anyway (and fails,
because of missing/broken kernel-devel package).
DKMS already have appropriate (rpm/dpkg) hooks for new kernel
installation, so actually needed modules should be build in template on
kernel update/install anyway.
This saves about 2s from VM startup time.
