proposed additions to sys/conf/std

["Jonathan A. Kollasch" <jakllsch%kollasch.net@localhost>]

I propose adding

pseudo-device drvctl

and/or

options BUFQ_PRIOCSCAN

to src/sys/conf/std.

The reasons I even bring this up:
 - Many kernels are missing drvctl and thus do not support disk wedges
   (this is arguably due to a flaw in the design of disk wedges, but
   that's a another bikeshed).
 - BUFQ_PRIOCSCAN is superior to BUFQ_DISKSORT, and in fact
   BUFQ_DISKSORT is actually inferior to BUFQ_FCFS in terms of
   interactive disk I/O responsiveness.  There are many kernels that
   default to BUFQ_DISKSORT due to not explicitly adding BUFQ_PRIOCSCAN.

The ominous "
# "it's commonly used" is NOT a good reason to enable options here.
" line has me a bit apprehensive.  However, pseudo-device cpuctl is there
already.  There are some options that are there for historical reasons,
so this is sort of a slippery slope.  Do we need a new config file for
standard-but-optional-options?

        Jonathan Kollasch