Remove range_s VEC

Remove range_s VEC

This changes the "optimized_out" and "unavailable" VECs in struct
value to be std::vectors, and then fixes up all the uses.

gdb/ChangeLog
2018-04-06  Tom Tromey  <tom@tromey.com>

	* value.c (range_s): Remove typedef, VEC.
	(struct range): Add operator<.
	(range_lessthan): Remove.
	(ranges_contain): Change type.
	(~value): Update.
	(struct value) <unavailable, optimized_out>: Now std::vector.
	(value_entirely_available)
	(value_entirely_covered_by_range_vector)
	(value_entirely_unavailable, value_entirely_optimized_out):
	Update.
	(insert_into_bit_range_vector): Change argument type.
	(find_first_range_overlap): Likewise.
	(struct ranges_and_idx, value_contents_bits_eq)
	(require_not_optimized_out, require_available): Update.
	(ranges_copy_adjusted): Change argument types.
	(value_optimized_out, value_copy, value_fetch_lazy): Update.