Bug#366514: Automatic upgrade from Xfree86 needs to fix mouse

[Peter Chubb <peter@chubb.wattle.id.au>]

Package: xserver-xorg
Version: 7.0.17

I tried to upgrade from Xserver-xfree86 to xserver-xorg.  The
XF86Config-4 file had the mouse device as /dev/input/mice.  The
rewritten xorg.conf file had /dev/mouse, which doesn't exist on my
system.   It looks as though the info in XF86Config-4 is not consulted
for the upgrade.