r22661: optimize the handling of directly triggered timed events:

r22661: optimize the handling of directly triggered timed events:

- if someone adds a timed_event with a zero timeval
  we now avoid serval gettimeofday() calls and the
  event handler doesn't get the current time when it's
  called, instead we also pass a zero timeval

- this also makes sure multiple timed events with a zero timeval
  are processed in the order there're added.

the little benchmark shows that processing 2000000 directly timed events
is now much faster, while avoiding syscalls at all!

> time ./evtest (with the old code)

real    0m6.388s
user    0m1.740s
sys     0m4.632s
> time ./evtest (with the new code)

real    0m1.498s
user    0m1.496s
sys     0m0.004s
metze@SERNOX:~/devel/samba/4.0/samba4-ci/source> cat evtest.c
#include <stdio.h>
#include <stdint.h>
#include <sys/time.h>
#include <talloc.h>
#include <events.h>

static void dummy_fde_handler(struct event_context *ev_ctx, struct fd_event *fde,
                              uint16_t flags, void *private_data)
{
}

static void timeout_handler(struct event_context *ev, struct timed_event *te,
                            struct timeval tval, void *private_data)
{
        uint32_t *countp = (uint32_t *)private_data;
        (*countp)++;
        if (*countp > 2000000) exit(0);
        event_add_timed(ev, ev, tval, timeout_handler, countp);
}

int main(void)
{
        struct event_context *ev;
        struct timeval tval =  { 0, 0 };
        uint32_t count = 0;
        ev = event_context_init(NULL);
        event_add_fd(ev, ev, 0, 0, dummy_fde_handler, NULL);
        event_add_timed(ev, ev, tval, timeout_handler, &count);
        return event_loop_wait(ev);
}
(This used to be commit 4db64b4ce2320b88d648078cbf86385f6fb44f1f)