#6 2.5.3: swapon crashes on missing device

[Kenn Humborg]

When booting 2.5.3 and on the vaxroot filesystem, the
kernel crashes in sys_swapon() if the /dev/sda2...swap...
line is present in /etc/fstab.

Since this is core kernel code, I'm going to leave this
for a
few versions and see if someone else fixes it, before I
revisit it.