re: kern/49728: crash in uhid

[matthew green <mrg%eterna.com.au@localhost>]

AFAICT, i failed to properly protect sc_q when converting this
driver on the usbmp branch, and this is likely a list being
updated while also traversed.  i don't have a fix, but it should
not be a big deal.

there might also be the same problem in some of the other drivers
so i plan to survey them all that i've updated for this (there
aren't many to check, fortunately.)

of course, anyone else is else welcome to look at this, i may
not find time for a week or more.


.mrg.