Backport platform specific code to python2 (#6772)

stdlib/@python2/tty.pyi

@@ -1,15 +1,16 @@
+import sys
 from typing import IO, Union
 
 _FD = Union[int, IO[str]]
 
-# XXX: Undocumented integer constants
-IFLAG: int
-OFLAG: int
-CFLAG: int
-LFLAG: int
-ISPEED: int
-OSPEED: int
-CC: int
-
-def setraw(fd: _FD, when: int = ...) -> None: ...
-def setcbreak(fd: _FD, when: int = ...) -> None: ...
+if sys.platform != "win32":
+    # XXX: Undocumented integer constants
+    IFLAG: int
+    OFLAG: int
+    CFLAG: int
+    LFLAG: int
+    ISPEED: int
+    OSPEED: int
+    CC: int
+    def setraw(fd: _FD, when: int = ...) -> None: ...
+    def setcbreak(fd: _FD, when: int = ...) -> None: ...