Apply fixes, remove duplicates.

Apply fixes to _random, cStringIO, errno, operator, sys, zlib, etc.; also,
remove duplicate 2.7/math.pyi, 2.7/marshal.pyi.

builtins/2.7/gc.pyi

@@ -1,4 +1,4 @@
-# Stubs for gc (Python 2)
+"""Stubs for the 'gc' module."""
 
 from typing import List, Any, Tuple
 
@@ -6,8 +6,8 @@ def enable() -> None: ...
 def disable() -> None: ...
 def isenabled() -> bool: ...
 def collect(generation: int = None) -> int: ...
-def set_debug(flags: Any) -> None: ...
-def get_debug() -> Any: ...
+def set_debug(flags: int) -> None: ...
+def get_debug() -> int: ...
 def get_objects() -> List[Any]: ...
 def set_threshold(threshold0: int, threshold1: int = None, threshold2: int = None) -> None: ...
 def get_count() -> Tuple[int, int, int]: ...