Change kernel module code to build against the API changes in kernel 4.20 - This change
adds file "fixes_for_4.20".
- Require(pre) virtualbox by the -qt package: otherewise it might
happen that virtualbox-qt is installed before virtualbox, which
then results in files being assigned to group 'root' instead of
'vboxusers', as the group is only created later.
OBS-URL: https://build.opensuse.org/package/show/Virtualization/virtualbox?expand=0&rev=448
