Add a generic 'ring the bell' function (console bell on Linux and BSD,
/dev/audio on Solaris), and add DDX functions for this.  Make this the
core keyboard's bell.
Port Xvfb and Xnest to this.
Port XFree86 to this, with OS-specific hooks for Linux, BSD, and Solaris
taken from foo_io.c in the old layer.

Just short-circuit the change core keyboard/pointer requests.

Add support for CLOCK_MONOTONIC from clock_gettime, and use that in
GetTimeInMillis() if available, falling back to the old gettimeofday()
implementation.

This is _slightly_ faster on some 64-bit architectures, and _slightly_
slower on others (though barely measurable).

Add motion history support (sort of based on the XFree86 DDX's
implementation) to the DIX.

Try to make sure DeviceIntRec and friends stay the same size,
regardless of whether or not XKB is enabled.

Add untested first guess at what GetProximityEvents should look like.