Make vmdaemon timeout configurable

[trasz]

Summary

Make vmdaemon timeout configurable, so that one can adjust how often it runs.

Here's a trick: set this to 1, then run 'limits -m 0 sh', then run whatever you want with 'ktrace -it XXX', and observe how the working set changes over time.

[kib]

What is the purpose ?

sys/vm/vm_swapout.c

469

Why this blank line is needed ?

[trasz]

Whitespace.