Tweaks to ranger API routines.

Tweaks to ranger API routines.

Remove the gcc_assert wrappers that contain statements that need to be
executed.
Audit routines to ensure range is set to UNDEFINED when false is returned.

	* gimple-range-gori.cc (gori_compute_cache::cache_stmt): Accumulate
	return values and only set cache when everything returned true.
	* gimple-range.cc (get_tree_range): Set the return range to UNDEFINED
	when the range isn't supported.
	(gimple_ranger::calc_stmt): Return varying if the type is supported,
	even if the stmt processing failed.  False otherwise.
	(range_of_builtin_ubsan_call): Don't use gcc_assert.
	(range_of_builtin_call): Ditto.
	(gimple_ranger::range_of_cond_expr): Ditto.
	(gimple_ranger::range_of_expr): Ditto
	(gimple_ranger::range_on_entry): Ditto.
	(gimple_ranger::range_on_exit): Ditto.
	(gimple_ranger::range_on_edge): DItto.
	(gimple_ranger::range_of_stmt): Don't use gcc_assert, and initialize
	return value to UNDEFINED.