Split stdlib into Python 2 and 3 versions (#5442)

All new files in stdlib/@python2 are straight copies of the
corresponding files in stdlib.

stdlib/@python2/wave.pyi

@@ -0,0 +1,74 @@
+import sys
+from typing import IO, Any, BinaryIO, NamedTuple, NoReturn, Optional, Text, Tuple, Union
+
+_File = Union[Text, IO[bytes]]
+
+class Error(Exception): ...
+
+WAVE_FORMAT_PCM: int
+
+if sys.version_info >= (3, 0):
+    class _wave_params(NamedTuple):
+        nchannels: int
+        sampwidth: int
+        framerate: int
+        nframes: int
+        comptype: str
+        compname: str
+
+else:
+    _wave_params = Tuple[int, int, int, int, str, str]
+
+class Wave_read:
+    def __init__(self, f: _File) -> None: ...
+    if sys.version_info >= (3, 0):
+        def __enter__(self) -> Wave_read: ...
+        def __exit__(self, *args: Any) -> None: ...
+    def getfp(self) -> Optional[BinaryIO]: ...
+    def rewind(self) -> None: ...
+    def close(self) -> None: ...
+    def tell(self) -> int: ...
+    def getnchannels(self) -> int: ...
+    def getnframes(self) -> int: ...
+    def getsampwidth(self) -> int: ...
+    def getframerate(self) -> int: ...
+    def getcomptype(self) -> str: ...
+    def getcompname(self) -> str: ...
+    def getparams(self) -> _wave_params: ...
+    def getmarkers(self) -> None: ...
+    def getmark(self, id: Any) -> NoReturn: ...
+    def setpos(self, pos: int) -> None: ...
+    def readframes(self, nframes: int) -> bytes: ...
+
+class Wave_write:
+    def __init__(self, f: _File) -> None: ...
+    if sys.version_info >= (3, 0):
+        def __enter__(self) -> Wave_write: ...
+        def __exit__(self, *args: Any) -> None: ...
+    def setnchannels(self, nchannels: int) -> None: ...
+    def getnchannels(self) -> int: ...
+    def setsampwidth(self, sampwidth: int) -> None: ...
+    def getsampwidth(self) -> int: ...
+    def setframerate(self, framerate: float) -> None: ...
+    def getframerate(self) -> int: ...
+    def setnframes(self, nframes: int) -> None: ...
+    def getnframes(self) -> int: ...
+    def setcomptype(self, comptype: str, compname: str) -> None: ...
+    def getcomptype(self) -> str: ...
+    def getcompname(self) -> str: ...
+    def setparams(self, params: _wave_params) -> None: ...
+    def getparams(self) -> _wave_params: ...
+    def setmark(self, id: Any, pos: Any, name: Any) -> NoReturn: ...
+    def getmark(self, id: Any) -> NoReturn: ...
+    def getmarkers(self) -> None: ...
+    def tell(self) -> int: ...
+    # should be any bytes-like object after 3.4, but we don't have a type for that
+    def writeframesraw(self, data: bytes) -> None: ...
+    def writeframes(self, data: bytes) -> None: ...
+    def close(self) -> None: ...
+
+# Returns a Wave_read if mode is rb and Wave_write if mode is wb
+def open(f: _File, mode: Optional[str] = ...) -> Any: ...
+
+if sys.version_info < (3, 9):
+    openfp = open