Add fchmod and lchmod for Windows on 3.13 (#12662)

stdlib/@tests/stubtest_allowlists/win32-py313.txt

@@ -1,11 +1,7 @@
 # New in py313 (triage these!)
-nt.fchmod
-nt.lchmod
 ntpath.exists
 ntpath.lexists
 ntpath.splitroot
-os.fchmod
-os.lchmod
 os.path.exists
 os.path.lexists
 

stdlib/nt.pyi

@@ -107,5 +107,7 @@ if sys.platform == "win32":
             listvolumes as listvolumes,
             set_blocking as set_blocking,
         )
+    if sys.version_info >= (3, 13):
+        from os import fchmod as fchmod, lchmod as lchmod
 
     environ: dict[str, str]

stdlib/os/__init__.pyi

@@ -673,7 +673,6 @@ if sys.version_info >= (3, 12) or sys.platform != "win32":
     def set_blocking(fd: int, blocking: bool, /) -> None: ...
 
 if sys.platform != "win32":
-    def fchmod(fd: int, mode: int) -> None: ...
     def fchown(fd: int, uid: int, gid: int) -> None: ...
     def fpathconf(fd: int, name: str | int, /) -> int: ...
     def fstatvfs(fd: int, /) -> statvfs_result: ...
@@ -754,7 +753,6 @@ def chmod(path: FileDescriptorOrPath, mode: int, *, dir_fd: int | None = None, f
 if sys.platform != "win32" and sys.platform != "linux":
     def chflags(path: StrOrBytesPath, flags: int, follow_symlinks: bool = True) -> None: ...  # some flavors of Unix
     def lchflags(path: StrOrBytesPath, flags: int) -> None: ...
-    def lchmod(path: StrOrBytesPath, mode: int) -> None: ...
 
 if sys.platform != "win32":
     def chroot(path: StrOrBytesPath) -> None: ...
@@ -1179,3 +1177,12 @@ if sys.version_info >= (3, 13) and sys.platform == "linux":
     def timerfd_settime_ns(fd: FileDescriptor, /, *, flags: int = 0, initial: int = 0, interval: int = 0) -> tuple[int, int]: ...
     def timerfd_gettime(fd: FileDescriptor, /) -> tuple[float, float]: ...
     def timerfd_gettime_ns(fd: FileDescriptor, /) -> tuple[int, int]: ...
+
+if sys.version_info >= (3, 13) or sys.platform != "win32":
+    # Added to Windows in 3.13.
+    def fchmod(fd: int, mode: int) -> None: ...
+
+if sys.platform != "linux":
+    if sys.version_info >= (3, 13) or sys.platform != "win32":
+        # Added to Windows in 3.13.
+        def lchmod(path: StrOrBytesPath, mode: int) -> None: ...