S/390: Get rid of Y constraint in vector.md.

S/390: Get rid of Y constraint in vector.md.

This finally removes the Y constraint from the vector patterns while
folding some of them using a code iterator.

gcc/ChangeLog:

2016-03-01  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/subst.md (DSI_VI): New mode iterator.
	("addr_style_op_subst"): Use DSI_VI instead of DSI.
	* config/s390/vector.md ("vec_set<mode>"): Move expander before
	the insn definition.
	("*vec_set<mode>"): Change predicate and add alternative to
	support only either register or const_int operands as element
	selector.
	("*vec_set<mode>_plus"): New pattern to support reg + const_int
	operands.
	("vec_extract<mode>"): New expander.
	("*vec_extract<mode>"): New insn definition supporting reg and
	const_int element selectors.
	("*vec_extract<mode>_plus"): New insn definition supporting
	reg+const_int element selectors.
	("rotl<mode>3", "ashl<mode>3", "ashr<mode>3"): Merge into the
	following expander+insn definition.
	("<vec_shifts_name><mode>3"): New expander.
	("*<vec_shifts_name><mode>3<addr_style_op>"): New insn definition.

From-SVN: r233847