Recent USB mouse regression

A recent 8.0-CURRENT installation _without_ USB2 enabled or loaded from
`loader.conf' seems to have regressed a bit from a couple of weeks ago.

When I attach an old wired mouse I have at home:

  ums0: <Genius NetScroll + Mini Traveler, class 0/0, rev 1.10/1.10, addr 2> on uhub4
  ums0: 3 buttons and Z dir.

and run moused in debugging mode I can see mouse clicks being handled,
but mouse movement `dies' after a bit of time.  Pressing one of the
mouse buttons generates moused events like:

  moused: received char 0x83
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x7f
  moused: assembled full packet (len 8) 83,0,0,0,0,0,0,7f
  moused: ts:  3708 752982137
  moused:   :  3649 133538726
  moused: flags:00000001 buttons:00000001 obuttons:00000000
  moused: activity : buttons 0x00000001  dx 0  dy 0  dz 0
  moused: mstate[0]->count:1
  moused: button 1  count 1
  moused: received char 0x87
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x0
  moused: received char 0x7f
  moused: assembled full packet (len 8) 87,0,0,0,0,0,0,7f
  moused: ts:  3708 859980149
  moused: flags:00000001 buttons:00000000 obuttons:00000001
  moused: activity : buttons 0x00000000  dx 0  dy 0  dz 0
  moused: mstate[0]->count:1
  moused: button 1  count 0

but moving the mouse doesn't show anything in the log of moused, as if
the movement event were never delivered by the USB stack to `/dev/ums0'.

Some times moused starts receiving movement events for 1-2 seconds and
then they are gone again.

One of the ways I can reliably get the mouse in a `dead' state is by
typing in an xterm window.  When xterm hides the mouse pointer of X11,
mouse movement is gone for good.

A second mouse -- a wireless Microsoft mouse -- attaches as ums0 but
never delivers anything to moused:

  root: Unknown USB device: vendor 0x045e product 0x00e1 bus uhub4
  kernel: ums0: <Microsoft Microsoft Wireless Optical Mouse 1.00, class 0/0, rev 2.00/0.07, addr 2> on uhub4
  kernel: ums0: 5 buttons and Z dir.

Both of these used to work a couple of weeks ago, and I'm looking back
through history to find out when this started.

Is anyone else seeing something like this?