Simplify "isvoid".
Simplify "isvoid".

	* share/urbi/k1.u (isvoid): Simplify.

aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi