Raise max header size to accommodate large tokens.

The max header is exceeded in the following scenario
- Auth tokens built with a keystone v3 API catalog
- A catalog with approximately 8 or more endpoints defined

An equivalent fix will be required for all projects which use
eventlet.wsgi.

Copied from https://review.openstack.org/#/c/33362/

Closes-Bug: 1190149

Change-Id: I3fcb196b25a7a477b799c8dfa2ff5115977ca06d

cinder/wsgi.py

@@ -67,6 +67,9 @@ CONF.register_opts(socket_opts)
 
 LOG = logging.getLogger(__name__)
 
+# Raise the default from 8192 to accommodate large tokens
+eventlet.wsgi.MAX_HEADER_LINE = 16384
+
 
 class Server(object):
     """Server class to manage a WSGI server, serving a WSGI application."""