Revert new experimental libev backend due to time constraints

Due to time constraints I had to revert the new libev backend to the
service, I/O and signals monitor.  Employed instead is the tried and
tested signals based service monitor, with a small extension for an
additional I/O monitor using poll() for the I/O plugins to use.

Tried restoring the startx finit.conf directive on top of the service
implementation. However, it's currently not usable to run /usr/bin/startx
for any other user than root. I recommend using the examples/finit.conf
and run /usr/sbin/gdm instead.

finit.c:
        New run_loop() function, replaces libev ev_run().

helpers.c:
        Refactor start_process() into svc_start().

plugin.c:
        Add fds[] array for use in the io_monitor() called by the
        new run_loop().

signal.c:
        Ignore SIGCHLD. Handled by waitpid() in svc_monitor() now,
        which is called by the new run_loop().

svc.c:
        svc_register(): Optional @username parsing for the command line.
        svc_monitor(): Replaced libev callback with waitpid()
        svc_start(): Refactored to use most of helpers.c:start_process()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

signal.c

@@ -98,13 +98,7 @@ static void shutdown_handler(int sig, siginfo_t *info, void *UNUSED(ctx))
  */
 static void chld_handler(int UNUSED(sig), siginfo_t *UNUSED(info), void *UNUSED(ctx))
 {
-	int status;
-
-//	_d("Child %d died due to signal %d, harvesting.", info->si_pid, sig);
-	while (waitpid(-1, &status, WNOHANG) != 0) {
-		if (errno == ECHILD)
-			break;
-	}
+	/* Do nothing, the svc_monitor() is the designated child reaper. */
 }
 
 /*