Work around a version clash issue with os-client-config

Need to add the fixed_arguments arg to _validate_auth() so
os-client-config 1.19.1 and 1.20.0 can call our version properly.

Change-Id: I328e47ba2f8115e6b18bf1482fd4aa35056907a4

Author: Dean Troyer

openstackclient/common/client_config.py

@@ -148,11 +148,11 @@ def auth_config_hook(self, config):
         LOG.debug("auth_config_hook(): %s" % config)
         return config
 
-    def _validate_auth_ksc(self, config, cloud):
+    def _validate_auth_ksc(self, config, cloud, fixed_argparse=None):
         """Old compatibility hack for OSC, no longer needed/wanted"""
         return config
 
-    def _validate_auth(self, config, loader):
+    def _validate_auth(self, config, loader, fixed_argparse=None):
         """Validate auth plugin arguments"""
         # May throw a keystoneauth1.exceptions.NoMatchingPlugin