usbFindBusByVendor: don't leak a DIR buffer and FD

* src/util/hostusb.c (usbFindBusByVendor): Don't leak a DIR buffer
and file descriptor.

src/util/hostusb.c

 /*
- * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2009-2010 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -151,6 +151,7 @@ static int usbFindBusByVendor(virConnectPtr conn,
         ret = 0;
 
 error:
+    closedir (dir);
     return ret;
 }