Remove setting of STMT_VINFO_VECTYPE on non-dataref stmts

Remove setting of STMT_VINFO_VECTYPE on non-dataref stmts

The following removes early setting of STMT_VINFO_VECTYPE and as
side-effect early failing if we fail to compute a vector type.  The
latter is now ensured by SLP build.  The former is still temporarily
copied from the SLP tree during stmt analysis, and data reference
stmts will still have STMT_VINFO_VECTYPE given existing uses in
dependence and alignment analysis and peeling.

	* tree-vect-loop.cc (vect_determine_vectype_for_stmt_1): Remove.
	(vect_determine_vectype_for_stmt): Likewise.
	(vect_set_stmts_vectype): Likewise.
	(vect_analyze_loop_2): Do not call vect_set_stmts_vectype.
	* tree-vect-stmts.cc (vect_mark_stmts_to_be_vectorized): Detect
	irregular stmts early here.