qtest: Fix deadloop by running main loop AIO context's timers

qemu_clock_run_timers() only takes care of main_loop_tlg, we shouldn't
forget aio timer list groups.

Currently, the qemu_clock_deadline_ns_all (a few lines above) counts all
the timergroups of this clock type, including aio tlg, but we don't fire
them, so they are never cleared, which makes a dead loop.

For example, this function hangs when trying to drive throttled block
request queue with qtest clock_step.

Signed-off-by: Fam Zheng <famz@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1421661103-29153-1-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
