qvm-sync-clock: sync dom0 clock only when NTP sync succeeded, even with --force

Otherwise dom0 clock (initially almost ok) may be adjusted to totally
invalid timestamp of ClockVM (for example just after resume from S3
sleep).

qvm-tools/qvm-sync-clock

@@ -94,7 +94,7 @@ def main():
         else:
             print >> sys.stderr, 'Time sync failed! - Exiting'
             sys.exit(1)
-
+    else:
         # Use the date format based on RFC2822 to avoid localisation issues
         p = clock_vm.run('date -u -Iseconds', verbose=options.verbose,
                          gui=False, passio_popen=True, ignore_stderr=True)