perf ftrace: Add option -D/--delay to delay tracing

--pid=::

	Trace on existing process id (comma separated list).

-D::

--delay::

	Time (ms) to wait before starting tracing after program start.

-a::

--all-cpus::

	Force system-wide collection.  Scripts run without a <command>

	int			graph_noirqs;

	int			graph_verbose;

	int			graph_thresh;

	unsigned int		initial_delay;

};

struct filter_entry {

	/* display column headers */

	read_tracing_file_to_stdout("trace");

	if (!ftrace->initial_delay) {

		if (write_tracing_file("tracing_on", "1") < 0) {

			pr_err("can't enable tracing\n");

			goto out_close_fd;

		}

	}

	perf_evlist__start_workload(ftrace->evlist);

	if (ftrace->initial_delay) {

		usleep(ftrace->initial_delay * 1000);

		if (write_tracing_file("tracing_on", "1") < 0) {

			pr_err("can't enable tracing\n");

			goto out_close_fd;

		}

	}

	while (!done) {

		if (poll(&pollfd, 1, -1) < 0)

			break;

		     "size of per cpu buffer", parse_buffer_size),

	OPT_BOOLEAN(0, "inherit", &ftrace.inherit,

		    "trace children processes"),

	OPT_UINTEGER('D', "delay", &ftrace.initial_delay,

		     "ms to wait before starting tracing after program start"),

	OPT_END()

	};