qemu: Fix condition for checking vcpu when pinning vcpus

Previously we checked that the vcpu we are trying to set is in range of
the number of threads presented by qemu. The problem is that if the VM
is offline the count is 0. Since the condition subtracted 1 from the
count the number would overflow and the check would never trigger.

Change the condition for more sensible ones with specific error
messages.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1208434

src/qemu/qemu_driver.c

@@ -5150,10 +5150,17 @@ qemuDomainPinVcpuFlags(virDomainPtr dom,
 
     priv = vm->privateData;
 
-    if (vcpu > (priv->nvcpupids-1)) {
+    if ((flags & VIR_DOMAIN_AFFECT_LIVE) && vcpu >= vm->def->vcpus) {
         virReportError(VIR_ERR_INVALID_ARG,
-                       _("vcpu number out of range %d > %d"),
-                       vcpu, priv->nvcpupids - 1);
+                       _("vcpu %d is out of range of live cpu count %d"),
+                       vcpu, vm->def->vcpus);
+        goto endjob;
+    }
+
+    if ((flags & VIR_DOMAIN_AFFECT_CONFIG) && vcpu >= persistentDef->vcpus) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("vcpu %d is out of range of persistent cpu count %d"),
+                       vcpu, persistentDef->vcpus);
         goto endjob;
     }