* vmmouse_detect: A simple program that detects whether a vmmouse
   device is present.
 * hal-probe-vmmouse: A HAL callout script that uses vmmouse_detect
   and overrides input.x11_driver.
 * 11-x11-vmmouse.fdi: fdi descriptor that adds the callout for PS/2
   mice.

Additional 'configure' variables have been added to allow for overriding
HAL paths, although this shouldn't usually be necessary.