Add _locale module (#10859)

More accurately reflect the platform availability of several constants and functions in `locale`.

stdlib/_locale.pyi

@@ -0,0 +1,100 @@
+import sys
+from _typeshed import StrPath
+from collections.abc import Iterable, Mapping
+
+LC_CTYPE: int
+LC_COLLATE: int
+LC_TIME: int
+LC_MONETARY: int
+LC_NUMERIC: int
+LC_ALL: int
+CHAR_MAX: int
+
+def setlocale(category: int, locale: str | Iterable[str | None] | None = None) -> str: ...
+def localeconv() -> Mapping[str, int | str | list[int]]: ...
+
+if sys.version_info >= (3, 11):
+    def getencoding() -> str: ...
+
+def strcoll(__os1: str, __os2: str) -> int: ...
+def strxfrm(__string: str) -> str: ...
+
+# native gettext functions
+# https://docs.python.org/3/library/locale.html#access-to-message-catalogs
+# https://github.com/python/cpython/blob/f4c03484da59049eb62a9bf7777b963e2267d187/Modules/_localemodule.c#L626
+if sys.platform != "win32":
+    LC_MESSAGES: int
+
+    ABDAY_1: int
+    ABDAY_2: int
+    ABDAY_3: int
+    ABDAY_4: int
+    ABDAY_5: int
+    ABDAY_6: int
+    ABDAY_7: int
+
+    ABMON_1: int
+    ABMON_2: int
+    ABMON_3: int
+    ABMON_4: int
+    ABMON_5: int
+    ABMON_6: int
+    ABMON_7: int
+    ABMON_8: int
+    ABMON_9: int
+    ABMON_10: int
+    ABMON_11: int
+    ABMON_12: int
+
+    DAY_1: int
+    DAY_2: int
+    DAY_3: int
+    DAY_4: int
+    DAY_5: int
+    DAY_6: int
+    DAY_7: int
+
+    ERA: int
+    ERA_D_T_FMT: int
+    ERA_D_FMT: int
+    ERA_T_FMT: int
+
+    MON_1: int
+    MON_2: int
+    MON_3: int
+    MON_4: int
+    MON_5: int
+    MON_6: int
+    MON_7: int
+    MON_8: int
+    MON_9: int
+    MON_10: int
+    MON_11: int
+    MON_12: int
+
+    CODESET: int
+    D_T_FMT: int
+    D_FMT: int
+    T_FMT: int
+    T_FMT_AMPM: int
+    AM_STR: int
+    PM_STR: int
+
+    RADIXCHAR: int
+    THOUSEP: int
+    YESEXPR: int
+    NOEXPR: int
+    CRNCYSTR: int
+    ALT_DIGITS: int
+
+    def nl_langinfo(__key: int) -> str: ...
+
+    # This is dependent on `libintl.h` which is a part of `gettext`
+    # system dependency. These functions might be missing.
+    # But, we always say that they are present.
+    def gettext(__msg: str) -> str: ...
+    def dgettext(__domain: str | None, __msg: str) -> str: ...
+    def dcgettext(__domain: str | None, __msg: str, __category: int) -> str: ...
+    def textdomain(__domain: str | None) -> str: ...
+    def bindtextdomain(__domain: str, __dir: StrPath | None) -> str: ...
+    def bind_textdomain_codeset(__domain: str, __codeset: str | None) -> str | None: ...