SCHED_4BSD in RELENG_7 disturbs workflow

[Josh Carroll]

> Not to say that any problems that might have developed with SCHED_4BSD
> should not be fixed, but you should give SCHED_ULE a try since it brings
> benefits even for single CPU systems (e.g. better interactive response).

For my particular work load, 4BSD is actually faster than ULE in
RELENG_7. Specifically, on a Q6600 running ffmpeg -threads 8 to
transcode some H.264 video, 4BSD is about 5% faster. I took a sample
video and transcoded the first 120 seconds of it, and here are the
results (including a control from 6.2-RELEASE-p7/4BSD scheduler):

releng_6_2 (4BSD)   1:32.39
releng_7 (4BSD)       1:32.44
releng_7 (ULE)         1:37.15

This is obviously a different scenario from MySQL. So perhaps ULE
isn't as well tuned for cases like ffmpeg?

Josh