Add '_sqlite3' to BaseDefinition._mapping

jedi/api_classes.py

@@ -44,6 +44,7 @@ class BaseDefinition(object):
                'posix': 'os',
                '_io': 'io',
                '_functools': 'functools',
+               '_sqlite3': 'sqlite3',
                '__builtin__': '',
                'builtins': '',
                }