Tidy: remove reduc_xxx_optab migration code.

Tidy: remove reduc_xxx_optab migration code.

	* doc/md.texi (reduc_smin_@var{m}, reduc_smax_@var{m},
	reduc_umin_@var{m}, reduc_umax_@var{m}, reduc_splus_@var{m},
	reduc_uplus_@var{m}): Remove.
	* expr.c (expand_expr_real_2): Remove expansion path for
	reduc_[us](min|max|plus) optabs.
	* optabs-tree.c (scalar_reduc_to_vector): Remove.
	* optabs-tree.h (scalar_reduc_to_vector): Remove.
	* optabs.def (reduc_smax_optab, reduc_smin_optab, reduc_splus_optab,
	reduc_umax_optab, reduc_umin_optab, reduc_uplus_optab): Remove.
	* tree-vect-loop.c (vectorizable_reduction): Remove test for
	reduc_[us](min|max|plus) optabs.

From-SVN: r232373