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/zlib.pyi

@@ -1,6 +1,6 @@
 # Stubs for zlib (Python 2.7)
-#
-# NOTE: This stub was automatically generated by stubgen.
+
+class error(Exception): ...
 
 DEFLATED = ... # type: int
 DEF_MEM_LEVEL = ... # type: int
@@ -19,12 +19,18 @@ Z_SYNC_FLUSH = ... # type: int
 
 def adler32(data: str, value: int = ...) -> int: ...
 def compress(data: str, level: int = ...) -> str: ...
-# TODO: compressobj() returns a compress object
-def compressobj(level: int = ..., method: int = ..., wbits: int = ..., memlevel: int = ...,
-                strategy: int = ...): ...
 def crc32(data: str, value: int = ...) -> int: ...
 def decompress(data: str, wbits: int = ..., bufsize: int = ...) -> str: ...
-# TODO: decompressobj() returns a decompress object
-def decompressobj(wbits: int = ...): ...
 
-class error(Exception): ...
+class compressobj:
+    def __init__(level: int = ..., method: int = ..., wbits: int = ..., memlevel: int = ...,
+                 strategy: int = ...): ...
+    def compress(self, data: str) -> str: ...
+    def copy(self) -> _Compress: ...
+    def flush(self) -> NoneType: ...
+
+class decompressobj:
+    def __init__(wbits: int = ...): ...
+    def copy(self) -> _Compress: ...
+    def decompress(self, data: str) -> str: ...
+    def flush(self) -> NoneType: ...