IBM Z: Get rid of vec merge unspec

IBM Z: Get rid of vec merge unspec

This patch gets rid of the unspecs we were using for the vector merge
instruction and replaces it with generic rtx.

gcc/ChangeLog:

	* config/s390/s390-modes.def: Add more vector modes to support
	concatenation of two vectors.
	* config/s390/s390-protos.h (s390_expand_merge_perm_const): Add
	prototype.
	(s390_expand_merge): Likewise.
	* config/s390/s390.c (s390_expand_merge_perm_const): New function.
	(s390_expand_merge): New function.
	* config/s390/s390.md (UNSPEC_VEC_MERGEH, UNSPEC_VEC_MERGEL):
	Remove constant definitions.
	* config/s390/vector.md (V_HW_2): Add mode iterators.
	(VI_HW_4, V_HW_4): Rename VI_HW_4 to V_HW_4.
	(vec_2x_nelts, vec_2x_wide): New mode attributes.
	(*vmrhb, *vmrlb, *vmrhh, *vmrlh, *vmrhf, *vmrlf, *vmrhg, *vmrlg):
	New pattern definitions.
	(vec_widen_umult_lo_<mode>, vec_widen_umult_hi_<mode>)
	(vec_widen_smult_lo_<mode>, vec_widen_smult_hi_<mode>)
	(vec_unpacks_lo_v4sf, vec_unpacks_hi_v4sf, vec_unpacks_lo_v2df)
	(vec_unpacks_hi_v2df): Adjust expanders to emit non-unspec RTX for
	vec merge.
	* config/s390/vx-builtins.md (V_HW_4): Remove mode iterator. Now
	in vector.md.
	(vec_mergeh<mode>, vec_mergel<mode>): Use s390_expand_merge to
	emit vec merge pattern.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/vector/long-double-asm-in-out-hard-fp-reg.c:
	Instead of vpdi with 0 and 5 vmrlg and vmrhg are used now.
	* gcc.target/s390/vector/long-double-asm-inout-hard-fp-reg.c: Likewise.
	* gcc.target/s390/zvector/vec-types.h: New test.
	* gcc.target/s390/zvector/vec_merge.c: New test.