Annotations for remaining Python 3.8 additions (#3358)

* Add os.add_dll_directory()
* Add memfd_create() and flags
* Add type annotation to flags
* Add stat_result.st_reparse_tag and flags
* Add ncurses_version
* Add Path.link_to()
* Add Picker.reducer_override()
* Add plistlib.UID
* Add has_dualstack_ipv6() and create_server()
* Add shlex.join()
* Add SSL methods and fields
* Add Python 3.8 statistics functions and classes
* Remove obsolete sys.subversion
* Add sys.unraisablehook
* Add threading.excepthook
* Add get_native_id() and Thread.native_id
* Add Python 3.8 tkinter methods
* Add CLOCK_UPTIME_RAW
* Add SupportsIndex
* Add typing.get_origin() and get_args()
* Add unicodedata.is_normalized
* Add unittest.mock.AsyncMock

Currently this is just an alias for Any like Mock and MagicMock. All of
these classes should probably be sub-classing Any and add their own
methods. See also #3224.

* Add unittest cleanup methods
* Add IsolatedAsyncioTestCase
* Add ElementTree.canonicalize() and C14NWriterTarget
* cProfile.Profile can be used as a context manager
* Add asyncio task name handling
* mmap.flush() now always returns None
* Add posonlyargcount to CodeType

stdlib/3/tkinter/__init__.pyi

@@ -1,5 +1,6 @@
+import sys
 from types import TracebackType
-from typing import Any, Optional, Dict, Callable, Type
+from typing import Any, Optional, Dict, Callable, Tuple, Type, Union
 from tkinter.constants import *  # noqa: F403
 
 TclError: Any
@@ -389,6 +390,8 @@ class Canvas(Widget, XView, YView):
     def tag_lower(self, *args): ...
     lower: Any
     def move(self, *args): ...
+    if sys.version_info >= (3, 8):
+        def moveto(self, tagOrId: Union[int, str], x: str = ..., y: str = ...) -> None: ...
     def postscript(self, cnf=..., **kw): ...
     def tag_raise(self, *args): ...
     lift: Any
@@ -615,6 +618,9 @@ class PhotoImage(Image):
     def get(self, x, y): ...
     def put(self, data, to: Optional[Any] = ...): ...
     def write(self, filename, format: Optional[Any] = ..., from_coords: Optional[Any] = ...): ...
+    if sys.version_info >= (3, 8):
+        def transparency_get(self, x: int, y: int) -> bool: ...
+        def transparency_set(self, x: int, y: int, boolean: bool) -> None: ...
 
 class BitmapImage(Image):
     def __init__(self, name: Optional[Any] = ..., cnf=..., master: Optional[Any] = ..., **kw): ...
@@ -635,10 +641,15 @@ class Spinbox(Widget, XView):
     def scan(self, *args): ...
     def scan_mark(self, x): ...
     def scan_dragto(self, x): ...
-    def selection(self, *args): ...
+    def selection(self, *args: Any) -> Tuple[int, ...]: ...
     def selection_adjust(self, index): ...
     def selection_clear(self): ...
     def selection_element(self, element: Optional[Any] = ...): ...
+    if sys.version_info >= (3, 8):
+        def selection_from(self, index: int) -> None: ...
+        def selection_present(self) -> None: ...
+        def selection_range(self, start: int, end: int) -> None: ...
+        def selection_to(self, index: int) -> None: ...
 
 class LabelFrame(Widget):
     def __init__(self, master: Optional[Any] = ..., cnf=..., **kw): ...