[PATCH] Add configuration option for use of SIGIO handlers for input events

[Nix]

On 13 Sep 2009, Peter Hutterer spake thusly:
> I still see configurations with AllowEmptyInput off because there was a
> brief period when that fixed a certain broken setup. Now people use it
> because they read it somewhere and thought it's a good idea.

Actually I use it because with it off my keyboard is ignored unless HAL
is running, even as of X.org 1.6.x, and HAL is an unreliable POS which
failed to start for *years* for me, so I am reluctant to rely on it for
anything.

It's not all cargo-culting, unless you consider 'keyboard doesn't work,
turn this option on and now it does' to be cargo-culting.

(Note that this may have changed since 1.6.2, when I tried it last, but
I doubt it's changed much since then.)

(As an side, this is all with kbd+mouse. I have never managed to coerce
evdev into working at all, so I'm using kbd because, well, it doesn't
seem to have any disadvantages.  Maybe it can't deal with some key or
other that my keyboard doesn't even have. Maybe it's not good at dealing
with massive multilingualism, but I'm a monoglot. I don't know why you
push evdev so hard: kbd just works on every platform I've ever tried it
on, while evdev is an OS-specific thing requiring an off-by-default
kernel option to be turned on and I stll haven't managed to get working
even then. Maybe it needs some device permission to be tweaked from the
default as well, I don't know, it doesn't log it, and I don't much care
because, well, kbd works.)