pm-utils: do not leave background tasks - will be killed by systemd

qvm-sync-clock running in background is killed as soon as
qubes-suspend.service is terminated.
Additionally restore --verbose option, which was the case (implicitly)
in previous qvm-run based code.

Fixes QubesOS/qubes-issues#1795

(cherry picked from commit b19ba4dc2d)

pm-utils/01qubes-sync-vms-clock

@@ -8,7 +8,7 @@ sync_qubes_vms_wallclock()
     echo "Syncing VMs clock to: $DATE"
     qvm-run --all -u root --localcmd="date -u -Iseconds" "qubes.SetDateTime dom0"
     # Then try to sync from the network
-    /usr/bin/qvm-sync-clock &
+    /usr/bin/qvm-sync-clock
 }
 
 case "$1" in