Better AC_ARG_*.
Better AC_ARG_*.

	* build-aux/urbi-arg.m4 (_URBI_ARG): New.
	(URBI_ARG_ENABLE, URBI_ARGLIST_ENABLE): Use it.
	(URBI_ARG_WITH): New.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport