The EBuild for XMAME doesn't build in support for joysticks. Maybe a new use variable should be created for joystick support? If you add the code from the forum post above to the EBuild, it will complile with i386 support.
Does it break anything if its compiled in and you don't have a joystick?
Seems to work fine, I unplugged my joysticks, made sure that dev/input/js? and dev/js? were both not present, and XMAME still worked with keyboard input. I think it just enables joystick detection routines, but doesn't require them, which is why I made it always compile in support in the forum above. If other programs are like this (no idea?) it still might be nice to have a use variable for it.
Bass, we do not a USE flag for joystick, so just build it in.
fixed in xmame-0.60.1-r2