Rather than simply waiting silently and indefinitely for all
interrupt-driven configuration handlers to complete, print out a
diagnostic message every 60 second indicating which handlers are
still running. Do this at most 5 times per run so as to avoid
scrolling out any useful information from the kernel message
buffer.

The interval of 60 seconds was selected based on a best guess as
to the nature of "long enough" and may want to be tuned higher
or lower depending on real-world tolerances.

MFC after: 3 days
Discussed with: scottl