list: remove foldl_head.
list: remove foldl_head.

It is (1) not named properly (foldlHead), (2) not documented, (3) used
nowhere, (4) not tested.

	* share/urbi/list.u: Remove.

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