Fix asyncio IocpProactor version availability (#4121)

stdlib/3/asyncio/windows_events.pyi

@@ -44,11 +44,13 @@ class IocpProactor:
     def set_loop(self, loop: events.AbstractEventLoop) -> None: ...
     def select(self, timeout: Optional[int] = ...) -> List[futures.Future[Any]]: ...
     def recv(self, conn: socket.socket, nbytes: int, flags: int = ...) -> futures.Future[bytes]: ...
-    def recv_into(self, conn: socket.socket, buf: socket._WriteBuffer, flags: int = ...) -> futures.Future[Any]: ...
+    if sys.version_info >= (3, 7):
+        def recv_into(self, conn: socket.socket, buf: socket._WriteBuffer, flags: int = ...) -> futures.Future[Any]: ...
     def send(self, conn: socket.socket, buf: socket._WriteBuffer, flags: int = ...) -> futures.Future[Any]: ...
     def accept(self, listener: socket.socket) -> futures.Future[Any]: ...
     def connect(self, conn: socket.socket, address: bytes) -> futures.Future[Any]: ...
-    def sendfile(self, sock: socket.socket, file: IO[bytes], offset: int, count: int) -> futures.Future[Any]: ...
+    if sys.version_info >= (3, 7):
+        def sendfile(self, sock: socket.socket, file: IO[bytes], offset: int, count: int) -> futures.Future[Any]: ...
     def accept_pipe(self, pipe: socket.socket) -> futures.Future[Any]: ...
     async def connect_pipe(self, address: bytes) -> windows_utils.PipeHandle: ...
     def wait_for_handle(self, handle: windows_utils.PipeHandle, timeout: Optional[int] = ...) -> bool: ...

tests/stubtest_whitelists/win32-py35.txt

@@ -2,10 +2,6 @@ _codecs.oem_decode
 _codecs.oem_encode
 _winapi.GetACP
 _winapi.GetFileType
-asyncio.IocpProactor.recv_into
-asyncio.IocpProactor.sendfile
-asyncio.windows_events.IocpProactor.recv_into
-asyncio.windows_events.IocpProactor.sendfile
 ntpath.splitunc
 os.path.splitunc
 os.path.splitunc

tests/stubtest_whitelists/win32-py36.txt

@@ -1,9 +1,5 @@
 _winapi.GetACP
 _winapi.GetFileType
-asyncio.IocpProactor.recv_into
-asyncio.IocpProactor.sendfile
-asyncio.windows_events.IocpProactor.recv_into
-asyncio.windows_events.IocpProactor.sendfile
 hashlib.scrypt
 ntpath.splitunc
 os.path.splitunc