[RS6000] Migrate from reduc_xxx to reduc_xxx_scal optabs

[RS6000] Migrate from reduc_xxx to reduc_xxx_scal optabs

	* config/rs6000/altivec.md (reduc_splus_<mode>): Rename to...
	(reduc_plus_scal_<mode>): ...this, add rs6000_expand_vector_extract.
	(reduc_uplus_v16qi): Remove.

	* config/rs6000/vector.md (VEC_reduc_name): Change "splus" to "plus".
	(reduc_<VEC_reduc_name>_v2df): Remove.
	(reduc_<VEC_reduc_name>_v4sf): Remove.
	(reduc_<VEC_reduc:VEC_reduc_name>_scal_<VEC_F:name>): New.

	* config/rs6000/vsx.md (vsx_reduc_<VEC_reduc_name>_v2df): Declare
	gen_ function by removing * prefix.
	(vsx_reduc_<VEC_reduc_name>_v4sf): Likewise.

From-SVN: r227965