Proper way to remove never used ioctls

[Vladimir Kondratyev]

Hi,

Our sys/mouse.h header has a definition of MOUSE_GETVARS and 
MOUSE_SETVARS ioctls which are not documented and only stubbed in a few 
drivers: mse(4), psm(4) and syscon's sysmouse(4). The only exception is 
MOUSE_GETVARS implemented in psm(4)

Given the fact that they were introduced 20 years ago, implementation 
was never completed and googling on them shows no traces of usage in 
indexed universe, is it acceptable to just drop both defines and 
implementation w.o. leaving any COMPAT_FREEBSD shims?

-- 
WBR
Vladimir Kondratyev