* tree-vectorizer.c: Depend on langhooks.h.
	(supportable_widening_operation): Add two arguments. Support double
	type conversions.
	(supportable_narrowing_operation): Likewise.
	* tree-vectorizer.h (supportable_widening_operation): Add two
	arguments.
	(supportable_narrowing_operation): Likewise.
	* tree-vect-patterns.c (vect_recog_widen_mult_pattern) : Call
	supportable_widening_operation with correct arguments.
	* tree-vect-transform.c (vectorizable_conversion): Likewise.
	(vectorizable_type_demotion): Support double type conversions.
	(vectorizable_type_promotion): Likewise.
	* Makefile.in (tree-vectorizer.o): Depend on langhooks.h.

From-SVN: r138988