eventstat won't work on 4.11+ kernels because /proc/timer_stats has been removed

Timer stats were removed from the kernel with the following commit:

commit dfb4357da6ddbdf57d583ba64361c9d792b0e0b1
Author: Kees Cook <email address hidden>
Date: Wed Feb 8 11:26:59 2017 -0800

    time: Remove CONFIG_TIMER_STATS

    Currently CONFIG_TIMER_STATS exposes process information across namespaces:

    kernel/time/timer_list.c print_timer():

            SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);

    /proc/timer_list:

     #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570

    Given that the tracer can give the same information, this patch entirely
    removes CONFIG_TIMER_STATS.

So we're now getting:

sudo ./eventstat
Cannot open /proc/timer_stats, errno=2 (No such file or directory)

This should be fixed. Unfortunately the pid info does not appear in /proc/timer_list, so perhaps some kind of BPF magic needs to be added to get this info. Anyway, it's a pain to implement.