Improve typing of sysconfig.get_config_var(s) (#11454)

stubs/setuptools/setuptools/_distutils/sysconfig.pyi

@@ -1,12 +1,20 @@
-from collections.abc import Mapping
+from typing import Literal, overload
+from typing_extensions import deprecated
 
 from setuptools._distutils.ccompiler import CCompiler
 
 PREFIX: str
 EXEC_PREFIX: str
 
+@overload
+@deprecated("SO is deprecated, use EXT_SUFFIX. Support will be removed when this module is synchronized with stdlib Python 3.11")
+def get_config_var(name: Literal["SO"]) -> int | str | None: ...
+@overload
 def get_config_var(name: str) -> int | str | None: ...
-def get_config_vars(*args: str) -> Mapping[str, int | str]: ...
+@overload
+def get_config_vars() -> dict[str, str | int]: ...
+@overload
+def get_config_vars(arg: str, /, *args: str) -> list[str | int]: ...
 def get_config_h_filename() -> str: ...
 def get_makefile_filename() -> str: ...
 def get_python_inc(plat_specific: bool = ..., prefix: str | None = ...) -> str: ...