[generic] Fix access to removed function in python 3.4

The `Request.get_origin_req_host` method was deprecated in 3.3, use the
 `origin_req_host` property if it's not available, see http://docs.python.org/3.3/library/urllib.request.html#urllib.request.Request.get_origin_req_host.

youtube_dl/extractor/generic.py

@@ -185,9 +185,14 @@ class GenericIE(InfoExtractor):
                     newurl = newurl.replace(' ', '%20')
                     newheaders = dict((k,v) for k,v in req.headers.items()
                                       if k.lower() not in ("content-length", "content-type"))
+                    try:
+                        # This function was deprecated in python 3.3 and removed in 3.4
+                        origin_req_host = req.get_origin_req_host()
+                    except AttributeError:
+                        origin_req_host = req.origin_req_host
                     return HEADRequest(newurl,
                                        headers=newheaders,
-                                       origin_req_host=req.get_origin_req_host(),
+                                       origin_req_host=origin_req_host,
                                        unverifiable=True)
                 else:
                     raise compat_urllib_error.HTTPError(req.get_full_url(), code, msg, headers, fp)