[util] Move compatibility functions out of util

utils is large enough without these compatibility functions.

Everything that is present in newer versions of Python (i.e. with dev Python it's just an import) goes into compat.py .
Everything else (i.e. youtube-dl-specific helpers) goes into utils.py .

youtube_dl/extractor/laola1tv.py

@@ -4,6 +4,7 @@ import random
 import re
 
 from .common import InfoExtractor
+from ..utils import ExtractorError
 
 
 class Laola1TvIE(InfoExtractor):