Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/@python2/fcntl.pyi

@@ -0,0 +1,82 @@
+from _typeshed import FileDescriptorLike
+from typing import Any, Union
+
+FASYNC: int
+FD_CLOEXEC: int
+
+DN_ACCESS: int
+DN_ATTRIB: int
+DN_CREATE: int
+DN_DELETE: int
+DN_MODIFY: int
+DN_MULTISHOT: int
+DN_RENAME: int
+F_DUPFD: int
+F_EXLCK: int
+F_GETFD: int
+F_GETFL: int
+F_GETLEASE: int
+F_GETLK: int
+F_GETLK64: int
+F_GETOWN: int
+F_GETSIG: int
+F_NOTIFY: int
+F_RDLCK: int
+F_SETFD: int
+F_SETFL: int
+F_SETLEASE: int
+F_SETLK: int
+F_SETLK64: int
+F_SETLKW: int
+F_SETLKW64: int
+F_SETOWN: int
+F_SETSIG: int
+F_SHLCK: int
+F_UNLCK: int
+F_WRLCK: int
+I_ATMARK: int
+I_CANPUT: int
+I_CKBAND: int
+I_FDINSERT: int
+I_FIND: int
+I_FLUSH: int
+I_FLUSHBAND: int
+I_GETBAND: int
+I_GETCLTIME: int
+I_GETSIG: int
+I_GRDOPT: int
+I_GWROPT: int
+I_LINK: int
+I_LIST: int
+I_LOOK: int
+I_NREAD: int
+I_PEEK: int
+I_PLINK: int
+I_POP: int
+I_PUNLINK: int
+I_PUSH: int
+I_RECVFD: int
+I_SENDFD: int
+I_SETCLTIME: int
+I_SETSIG: int
+I_SRDOPT: int
+I_STR: int
+I_SWROPT: int
+I_UNLINK: int
+LOCK_EX: int
+LOCK_MAND: int
+LOCK_NB: int
+LOCK_READ: int
+LOCK_RW: int
+LOCK_SH: int
+LOCK_UN: int
+LOCK_WRITE: int
+
+# TODO All these return either int or bytes depending on the value of
+# cmd (not on the type of arg).
+def fcntl(fd: FileDescriptorLike, op: int, arg: Union[int, bytes] = ...) -> Any: ...
+
+# TODO: arg: int or read-only buffer interface or read-write buffer interface
+def ioctl(fd: FileDescriptorLike, op: int, arg: Union[int, bytes] = ..., mutate_flag: bool = ...) -> Any: ...
+def flock(fd: FileDescriptorLike, op: int) -> None: ...
+def lockf(fd: FileDescriptorLike, op: int, length: int = ..., start: int = ..., whence: int = ...) -> Any: ...