[vbox-dev] Missing global with kernel 4.14-rcX

[Larry Finger]

In kernel 4.14, the functions vfs_read() and vfs_write() are no longer exported. 
This change causes vboxpci.ko to fail when it is loaded as it appears to need 
vfs_read().

I searched the VB source code, but I do not see any direct reference to 
vfs_read(). Why is it needed? What needs to change for kernel 4.14>

My VM's do not need vboxpci, and a quick test shows that they run under 4.14-rc1.

Thanks,
Larry