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
odoo/http.py
if "lang" not in httprequest.session.context:
            alang = httprequest.accept_languages.best or "en-US"
            try:
                code, territory, _, _ = babel.core.parse_locale(alang, sep='-')
                if territory:
                    lang = '%s_%s' % (code, territory)
                else:
                    lang = babel.core.LOCALE_ALIASES[code]
            except (ValueError, KeyError):
                lang = 'en_US'
            httprequest.session.context["lang"] = lang
    def get_request(self, httprequest):
        
        if httprequest.args.get('jsonp'):
            return JsonRequest(httprequest)
        if httprequest.mimetype in ("application/json", "application/json-rpc"):
            return JsonRequest(httprequest)
        else:
            return HttpRequest(httprequest)
    def get_response(self, httprequest, result, explicit_session):