How do I completely disable suspend?

[Ryan Stone]

I have a laptop on which suspend/resume doesn't work.  I don't need
suspend/resume and don't want to spend the time debugging it.
However, there are some really annoying cases that can trigger a
suspend, and I find up having to power off the laptop to get it to
boot properly again.  How can I completely disable suspend?  Playing
with the sysctls under hw.acpi doesn't seem to actually do anything.