Remove ASSERT_EXPR.

Remove ASSERT_EXPR.

This removes all uses of ASSERT_EXPR except the internal one in ipa-*.

gcc/ChangeLog:

	* doc/gimple.texi: Remove ASSERT_EXPR references.
	* fold-const.cc (tree_expr_nonzero_warnv_p): Same.
	(fold_binary_loc): Same.
	(tree_expr_nonnegative_warnv_p): Same.
	* gimple-array-bounds.cc (get_base_decl): Same.
	* gimple-pretty-print.cc (dump_unary_rhs): Same.
	* gimple.cc (get_gimple_rhs_num_ops): Same.
	* pointer-query.cc (handle_ssa_name): Same.
	* tree-cfg.cc (verify_gimple_assign_single): Same.
	* tree-pretty-print.cc (dump_generic_node): Same.
	* tree-scalar-evolution.cc (scev_dfs::follow_ssa_edge_expr):Same.
	(interpret_rhs_expr): Same.
	* tree-ssa-operands.cc (operands_scanner::get_expr_operands): Same.
	* tree-ssa-propagate.cc
	(substitute_and_fold_dom_walker::before_dom_children): Same.
	* tree-ssa-threadedge.cc: Same.
	* tree-vrp.cc (overflow_comparison_p): Same.
	* tree.def (ASSERT_EXPR): Add note.
	* tree.h (ASSERT_EXPR_VAR): Remove.
	(ASSERT_EXPR_COND): Remove.
	* vr-values.cc (simplify_using_ranges::vrp_visit_cond_stmt):
	Remove comment.