qapi: Fix licensing of scripts

The scripts carry this copyright notice:

    # This work is licensed under the terms of the GNU GPLv2.
    # See the COPYING.LIB file in the top-level directory.

The sentences contradict each other, as COPYING.LIB contains the LGPL
2.1.  Michael Roth says this was a simple pasto, and he meant to refer
COPYING.  Let's fix that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

scripts/qapi-commands.py

@@ -7,8 +7,8 @@
 #  Anthony Liguori <aliguori@us.ibm.com>
 #  Michael Roth    <mdroth@linux.vnet.ibm.com>
 #
-# This work is licensed under the terms of the GNU GPLv2.
-# See the COPYING.LIB file in the top-level directory.
+# This work is licensed under the terms of the GNU GPL, version 2.
+# See the COPYING file in the top-level directory.
 
 from ordereddict import OrderedDict
 from qapi import *

scripts/qapi-types.py

@@ -6,8 +6,8 @@
 # Authors:
 #  Anthony Liguori <aliguori@us.ibm.com>
 #
-# This work is licensed under the terms of the GNU GPLv2.
-# See the COPYING.LIB file in the top-level directory.
+# This work is licensed under the terms of the GNU GPL, version 2.
+# See the COPYING file in the top-level directory.
 
 from ordereddict import OrderedDict
 from qapi import *

scripts/qapi-visit.py

@@ -7,8 +7,8 @@
 #  Anthony Liguori <aliguori@us.ibm.com>
 #  Michael Roth    <mdroth@linux.vnet.ibm.com>
 #
-# This work is licensed under the terms of the GNU GPLv2.
-# See the COPYING.LIB file in the top-level directory.
+# This work is licensed under the terms of the GNU GPL, version 2.
+# See the COPYING file in the top-level directory.
 
 from ordereddict import OrderedDict
 from qapi import *

scripts/qapi.py

@@ -8,8 +8,8 @@
 #  Anthony Liguori <aliguori@us.ibm.com>
 #  Markus Armbruster <armbru@redhat.com>
 #
-# This work is licensed under the terms of the GNU GPLv2.
-# See the COPYING.LIB file in the top-level directory.
+# This work is licensed under the terms of the GNU GPL, version 2.
+# See the COPYING file in the top-level directory.
 
 from ordereddict import OrderedDict
 import sys