qemu: unlock qemu driver before return from domain save

qemuDriverUnlock() wasn't called on 2 exit paths
* src/qemu/qemu_driver.c: fix qemudDomainSave() to always unlock
  the driver before exiting on error

src/qemu/qemu_driver.c

@@ -2068,13 +2068,13 @@ static int qemudDomainSave(virDomainPtr dom, const char *path)
             qemuReportError(VIR_ERR_OPERATION_FAILED,
                             "%s", _("Invalid save image format specified "
                                     "in configuration file"));
-            return -1;
+            goto cleanup;
         }
         if (!qemudCompressProgramAvailable(compressed)) {
             qemuReportError(VIR_ERR_OPERATION_FAILED,
                             "%s", _("Compression program for image format "
                                     "in configuration file isn't available"));
-            return -1;
+            goto cleanup;
         }
     }