[mixcloud] Fix _VALID_RE (fixes #2462)

Accept any character except `/` for uploader and the name, caused problems with non ASCII characters

youtube_dl/extractor/mixcloud.py

@@ -10,7 +10,7 @@ from ..utils import (
 
 
 class MixcloudIE(InfoExtractor):
-    _VALID_URL = r'^(?:https?://)?(?:www\.)?mixcloud\.com/([\w\d-]+)/([\w\d-]+)'
+    _VALID_URL = r'^(?:https?://)?(?:www\.)?mixcloud\.com/([^/]+)/([^/]+)'
     IE_NAME = 'mixcloud'
 
     _TEST = {