qemu: rework '-serial none'

Limiting ourselves to qemu without QEMU_CAPS_DEVICE capability, we
used '-serial none' only if there was no serial device defined in the
domain XML.  This means that if we want to have a possibility of the
device being defined in XML, but not used in the command-line
(e.g. when it's pointless), we'll fail to attach '-serial none' to the
command-line (when skipping the device's command-line building and the
device being the only one).

Since there is no such device, this patch doesn't actually do
anything, but enables easier future additions in this manner.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_command.c

 /*
  * qemu_command.c: QEMU command generation
  *
- * Copyright (C) 2006-2013 Red Hat, Inc.
+ * Copyright (C) 2006-2014 Red Hat, Inc.
  * Copyright (C) 2006 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -7710,6 +7710,7 @@ qemuBuildCommandLine(virConnectPtr conn,
     int vnc = 0;
     int spice = 0;
     int usbcontroller = 0;
+    int actualSerials = 0;
     bool usblegacy = false;
     bool mlock = false;
     int contOrder[] = {
@@ -8806,11 +8807,7 @@ qemuBuildCommandLine(virConnectPtr conn,
         virCommandAddArgBuffer(cmd, &opt);
     }
 
-    if (!def->nserials) {
-        /* If we have -device, then we set -nodefault already */
-        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))
-            virCommandAddArgList(cmd, "-serial", "none", NULL);
-    } else {
+    if (def->nserials) {
         for (i = 0; i < def->nserials; i++) {
             virDomainChrDefPtr serial = def->serials[i];
             char *devstr;
@@ -8834,9 +8831,14 @@ qemuBuildCommandLine(virConnectPtr conn,
                 virCommandAddArg(cmd, devstr);
                 VIR_FREE(devstr);
             }
+            actualSerials++;
         }
     }
 
+    /* If we have -device, then we set -nodefault already */
+    if (!actualSerials && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))
+            virCommandAddArgList(cmd, "-serial", "none", NULL);
+
     if (!def->nparallels) {
         /* If we have -device, then we set -nodefault already */
         if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))