Get rid of some gimple_expr_type uses

Get rid of some gimple_expr_type uses

This gets rid of a few gimple_expr_type uses.

2021-07-16  Richard Biener  <rguenther@suse.de>

	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Use
	the type of the LHS.
	(gimple_assign_nonnegative_warnv_p): Likewise.
	(gimple_call_nonnegative_warnv_p): Likewise.  Return false
	if the call has no LHS.
	* gimple.c (gimple_could_trap_p_1): Use the type of the LHS.
	* tree-eh.c (stmt_could_throw_1_p): Likewise.
	* tree-inline.c (insert_init_stmt): Likewise.
	* tree-ssa-loop-niter.c (get_val_for): Likewise.
	* tree-outof-ssa.c (ssa_is_replaceable_p): Use the type of
	the def.
	* tree-ssa-sccvn.c (init_vn_nary_op_from_stmt): Take a
	gassign *.  Use the type of the lhs.
	(vn_nary_op_lookup_stmt): Adjust.
	(vn_nary_op_insert_stmt): Likewise.