qemu: Issue rtc-reset-reinjection command after guest-set-time

qemu: Issue rtc-reset-reinjection command after guest-set-time

https://bugzilla.redhat.com/show_bug.cgi?id=1103245

An advice appeared there on the qemu-devel list [1]. When a domain is
suspended and then resumed guest kernel is not aware of this. So we've
introduced virDomainSetTime API that resets the time within guest
using qemu-ga. On the other hand, qemu itself is trying to make RTC
beat faster to catch the difference. But if we don't tell qemu that
guest's time was reset via the other method, both mechanisms are
applied resulting in again wrong guest time. In order to avoid summing
both corrections we need to tell qemu that it should not use the RTC
injection if the guest time is set via guest agent.

1: http://www.mail-archive.com/qemu-devel@nongnu.org/msg236435.html

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>