rebuild kernel to add vn pseudo-device for swap file

[Dave [Hawk-Systems]]

Has a server halt last night because it ran out of swap space.  The server is
slated for upgrade this month anyway (currently on 4.3) so I don't want to worry
about reslicing a partition.  Figured the easiest would be to add a swap file
for a temporary solution but the pseudo-device vn isn't in our customized
kernel.

What would be the minimal process to rebuild the kernel with this device, or is
the whole blown out proceedure requried as when we trimmed the kernel in the
first place.

Thanks

Dave