lto-wrapper: Use vec<cl_decoded_option> data type.

gcc/ChangeLog:

	* lto-wrapper.c (get_options_from_collect_gcc_options): Change
	return type.
	(append_option): Remove.
	(find_option): Rework to use the vector type.
	(remove_option): Remove.
	(merge_and_complain): Use vectors for cl_decoded_option data
	type arguments.
	(append_compiler_options): Likewise.
	(append_diag_options): Likewise.
	(append_linker_options): Likewise.
	(append_offload_options): Likewise.
	(compile_offload_image): Likewise.
	(compile_images_for_offload_targets): Likewise.
	(find_and_merge_options): Likewise.
	(run_gcc): Likewise.