proc: Update get proc_pid_cmdline() to use mm.h helpers

static int proc_pid_cmdline(struct task_struct *task, char *buffer)

{

	int res = 0;

	unsigned int len;

	struct mm_struct *mm = get_task_mm(task);

	if (!mm)

		goto out;

	if (!mm->arg_end)

		goto out_mm;	/* Shh! No looking before we're done */

 	len = mm->arg_end - mm->arg_start;

	if (len > PAGE_SIZE)

		len = PAGE_SIZE;

	res = access_process_vm(task, mm->arg_start, buffer, len, 0);

	// If the nul at the end of args has been overwritten, then

	// assume application is using setproctitle(3).

	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {

		len = strnlen(buffer, res);

		if (len < res) {

		    res = len;

		} else {

			len = mm->env_end - mm->env_start;

			if (len > PAGE_SIZE - res)

				len = PAGE_SIZE - res;

			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);

			res = strnlen(buffer, res);

		}

	}

out_mm:

	mmput(mm);

out:

	return res;

	return get_cmdline(task, buffer, PAGE_SIZE);

}

static int proc_pid_auxv(struct task_struct *task, char *buffer)