Run udevadm inside qemu in order to create the HW database index on
host.
The alternative would be to build a native version
of udevadm which would imply several things: split out systemd recipe,
create a common inc file and create a new recipe for udevadm native.
However, this latter solution might also add up to the build time
(the native recipe would need to run configure, make udevadm, install),
besides the time spent in the actual postinstall...
So, having the postinstall run through qemu is a good trade-off.
