Remove non-SLP vectorization factor determining

Remove non-SLP vectorization factor determining

The following removes the VF determining step from non-SLP stmts.
For now we keep setting STMT_VINFO_VECTYPE for all stmts, there are
too many places to fix, including some more complicated ones, so
this is defered for a followup.

Along this removes vect_update_vf_for_slp, merging the check for
present hybrid SLP stmts to vect_detect_hybrid_slp and fail analysis
early.  This also removes to essentially duplicate this check in
the stmt walk of vect_analyze_loop_operations.  Getting rid of that,
and performing some other checks earlier is also defered to a followup.

	* tree-vect-loop.cc (vect_determine_vf_for_stmt_1): Rename
	to ...
	(vect_determine_vectype_for_stmt_1): ... this and only set
	STMT_VINFO_VECTYPE.  Fail for single-element vector types.
	(vect_determine_vf_for_stmt): Rename to ...
	(vect_determine_vectype_for_stmt): ... this and only set
	STMT_VINFO_VECTYPE. Fail for single-element vector types.
	(vect_determine_vectorization_factor): Rename to ...
	(vect_set_stmts_vectype): ... this and only set STMT_VINFO_VECTYPE.
	(vect_update_vf_for_slp): Remove.
	(vect_analyze_loop_operations): Remove walk over stmts.
	(vect_analyze_loop_2): Call vect_set_stmts_vectype instead of
	vect_determine_vectorization_factor.  Set vectorization factor
	from LOOP_VINFO_SLP_UNROLLING_FACTOR.  Fail if vect_detect_hybrid_slp
	detects hybrid stmts or when vect_make_slp_decision finds
	nothing to SLP.
	* tree-vect-slp.cc (vect_detect_hybrid_slp): Move check
	whether we have any hybrid stmts here from vect_update_vf_for_slp
	* tree-vect-stmts.cc (vect_analyze_stmt): Remove loop over
	stmts.
	* tree-vectorizer.h (vect_detect_hybrid_slp): Update.