Daemon used false logic for determining whether there were any clients.
When the timer was inactive, it was activated if at least one of the
servers did not have clients.  So the bool was being flipped there and
back all the time in case there was one client, for example.

Initially introduced by fa142073.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1240283Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

So callers don't have to iterate over each server.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

VIR_APPEND_ELEMENT would clear @srv to NULL after it successfully
inserted it thus the reference count could not be increased afterwards.

Switch to VIR_APPEND_ELEMENT_COPY. This fixes crash after terminating
the daemon.

This allows to have more servers in one daemon which helps isolating
some resources.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>