Impacted versions: 8-11

## Current behavior:

If during an XMLRPC call you try to get anything from `http.request`, you'd get a `RuntimeError` such as this one:

```
Traceback (most recent call last):
  File "/opt/odoo/custom/src/odoo/odoo/service/wsgi_server.py", line 56, in xmlrpc_return
    result = odoo.http.dispatch_rpc(service, method, params)
  File "/opt/odoo/custom/src/odoo/odoo/http.py", line 118, in dispatch_rpc
    result = dispatch(method, params)
  File "/opt/odoo/custom/src/odoo/odoo/service/common.py", line 57, in dispatch
    return g[exp_method_name](*params)
  [...]
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 343, in __getattr__
    return getattr(self._get_current_object(), name)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 302, in _get_current_object
    return self.__local()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 135, in _lookup
    raise RuntimeError(\'object unbound\')
RuntimeError: object unbound
```

This renders imposible in practice to fix issues such as https://github.com/OCA/server-tools/issues/1125 or to implement https://github.com/odoo/odoo/pull/22212#issuecomment-380425764.

## Expected behavior:

XML-RPC calls should have request, since after all they belong to one. Otherwise, at least there should be an alternate way to access the request parameters.

Fix for v12: https://github.com/odoo/odoo/pull/24187

@Tecnativa
""" Two routes are available for XML-RPC
    /xmlrpc/<service> route returns faultCode as strings. This is a historic
    violation of the protocol kept for compatibility.
    /xmlrpc/2/<service> is a new route that returns faultCode as int and is
    therefore fully compliant.
    """
    if environ['REQUEST_METHOD'] == 'POST' and environ['PATH_INFO'].startswith('/xmlrpc/'):
        length = int(environ['CONTENT_LENGTH'])
        data = environ['wsgi.input'].read(length)
        
        string_faultcode = True
        service = environ['PATH_INFO'][len('/xmlrpc/'):]
        if environ['PATH_INFO'].startswith('/xmlrpc/2/'):
            service = service[len('2/'):]
            string_faultcode = False
        params, method = xmlrpclib.loads(data)
        try:
            result = odoo.http.dispatch_rpc(service, method, params)
            response = xmlrpclib.dumps((result,), methodresponse=1, allow_none=False)
        except Exception as e:
            if string_faultcode:
                response = xmlrpc_handle_exception_string(e)
            else:
                response = xmlrpc_handle_exception_int(e)
        return werkzeug.wrappers.Response(
            response=response,
            mimetype='text/xml',
        )(environ, start_response)
def application_unproxied(environ, start_response):