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
self.session['jsonp_request_%s' % (request_id,)] = self.httprequest.form['r']
                self.session.modified = True
                headers=[('Content-Type', 'text/plain; charset=utf-8')]
                r = werkzeug.wrappers.Response(request_id, headers=headers)
                return r
            self.jsonp_handler = handler
            return
        elif jsonp and args.get('r'):
            
            request = args.get('r')
        elif jsonp and request_id:
            
            request = self.session.pop('jsonp_request_%s' % (request_id,), '{}')
        else:
            
            request = self.httprequest.get_data().decode(self.httprequest.charset)
        
        try:
            self.jsonrequest = json.loads(request)
        except ValueError:
            msg = 'Invalid JSON data: %r' % (request,)
            _logger.info('%s: %s', self.httprequest.path, msg)
            raise werkzeug.exceptions.BadRequest(msg)
        self.params = dict(self.jsonrequest.get("params", {}))
        self.context = self.params.pop('context', dict(self.session.context))
    def _json_response(self, result=None, error=None):